{ "data": { "a": { "slug": "azure-text-to-speech", "name": "Azure AI Speech text-to-speech", "vendor": "Microsoft", "vendorUrl": "https://azure.microsoft.com/en-us/products/ai-services/text-to-speech", "kind": "model", "category": "text-to-speech", "summary": "Azure's text-to-speech service for generating spoken audio.", "url": "https://www.anchorterminal.com/tools/azure-text-to-speech", "markdownUrl": "https://www.anchorterminal.com/tools/azure-text-to-speech.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/azure-text-to-speech.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/azure-text-to-speech.json", "dns": "azure-text-to-speech.grade.anchorterminal.com", "repo": "https://github.com/Azure-Samples/cognitive-services-speech-sdk", "license": "MIT (samples), SDK under Microsoft's own licence", "transports": [ "http" ], "remoteUrl": "https://eastus.tts.speech.microsoft.com/cognitiveservices", "packages": [ { "registry": "pypi", "name": "azure-cognitiveservices-speech" }, { "registry": "npm", "name": "microsoft-cognitiveservices-speech-sdk" } ], "auth": "mixed", "authNotes": "`Ocp-Apim-Subscription-Key` header with a Speech resource key, or a Microsoft Entra ID bearer token. Endpoints are per region.", "pricing": "freemium", "pricingNotes": "Free F0 tier with 500,000 characters a month. Pay as you go in East US is $15 per 1M characters for Neural and Neural HD Flash voices and $22 for Neural HD, real time or batch. Commitment tiers from $960 a month for 80M characters (https://azure.microsoft.com/en-us/pricing/details/speech/). Microsoft AI lists MAI-Voice-2.1 at $22 and MAI-Voice-2.1-Flash at $15 per 1M characters in preview (https://microsoft.ai/models/mai-voice-2-1/).", "priceSummary": "$960 / mo", "where": "hosted", "x402": { "level": "no", "evidence": "No machine payment. Billing runs through a cloud account with a card or invoice.", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": 3450, "npmWeekly": 475621, "pypiWeekly": 1032532, "asOf": "2026-09-30" }, "docsUrl": "https://learn.microsoft.com/en-us/azure/ai-services/speech-service/text-to-speech", "capabilities": [ "speech.tts", "speech.streaming", "speech.voices", "speech.ssml", "speech.languages" ], "tags": [ "hosted", "freemium", "free-tier", "closed-source", "python", "typescript", "enterprise", "streaming", "batch", "async-jobs" ], "lastRelease": "2026-10-01", "graded": true, "anchor": { "graded": true, "score": 71.5, "grade": "BB", "agentReady": true, "rank": 157, "ranked": true, "rankOf": 1486, "categoryRank": 5, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 75, "maintenance": 80, "payments": 20, "reliability": 80, "schema": 65, "security": 90, "transparency": 86 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-05" }, "negative": 0, "verdict": "Real-time synthesis keeps neither the input text nor the output audio. An Azure subscription needs a card, even for the free F0 tier.", "bestFor": "Operators on Azure who need SSML control, many languages and voices, and enterprise access control.", "strengths": [ "Real-time synthesis keeps neither the input text nor the output audio", "Full SSML with speaking styles, prosody, phonemes, lexicons and up to 50 voice or audio tags a request", "Microsoft Entra ID with role-based access, or two rotatable keys", "Covered by Microsoft's online services SLA", "S0 starts at 30 requests a second and can be raised to 1,000" ], "weaknesses": [ "An Azure subscription needs a card, even for the free F0 tier", "No llms.txt and no OpenAPI file for text-to-speech found", "429s often reflect busy capacity for a voice in a region, which a quota increase doesn't fix", "The voice list comes back as one response per region with no paging documented", "MAI-Voice-2.1 and MAI-Voice-2.1-Flash, Microsoft's newest models, are public preview with no SLA" ], "agentNotes": [ "Send SSML with `\u003cspeak\u003e` and `\u003cvoice\u003e`, and set `X-Microsoft-OutputFormat` and `User-Agent`.", "On 429 retry with backoff, and try the voice's home region or another region rather than asking for more quota.", "Keep each real-time request under 10 minutes of audio, or use batch synthesis.", "Use Entra ID tokens instead of resource keys where the agent runs inside Azure.", "Name a MAI voice with its model suffix, such as `en-US-Harper:MAI-Voice-2.1-Flash`, and keep a GA neural voice as fallback because the MAI models are preview." ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 3.5, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "BB", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 71.5 } ], "editorialScores": { "ergonomics": 75, "maintenance": 80, "payments": 20, "reliability": 80, "schema": 65, "security": 90, "transparency": 80 }, "provenanceScore": 91, "checked": { "categories": { "ergonomics": "2026-10-05", "maintenance": "2026-10-05", "payments": "2026-10-05", "reliability": "2026-10-05", "schema": "2026-10-05", "security": "2026-10-05", "transparency": "2026-10-05" }, "last": "2026-10-05", "lastMoved": "2026-10-27", "oldest": "2026-10-05", "stale": false, "staleAfterDays": 90 } }, "connect": { "install": "pip install azure-cognitiveservices-speech # or: npm i microsoft-cognitiveservices-speech-sdk", "http": "curl -X POST \"https://eastus.tts.speech.microsoft.com/cognitiveservices/v1\" \\\n -H \"Ocp-Apim-Subscription-Key: $AZURE_SPEECH_KEY\" -H \"Content-Type: application/ssml+xml\" \\\n -H \"X-Microsoft-OutputFormat: audio-24khz-48kbitrate-mono-mp3\" -o speech.mp3 \\\n -d '\u003cspeak version=\"1.0\" xml:lang=\"en-US\"\u003e\u003cvoice name=\"en-US-AvaMultilingualNeural\"\u003eYour table is booked for seven.\u003c/voice\u003e\u003c/speak\u003e'" }, "letme": { "capability": "https://letme.dev/speech.tts", "tool": "https://letme.dev/azure-text-to-speech" }, "sameCompany": [ "azure-openai", "azure-foundry-fine-tuning", "azure-ai-content-safety", "azure-speech-to-text", "microsoft-agent-framework", "microsoft-execution-containers", "microsoft-entra-agent-id", "azure-key-vault", "bing-grounding", "azure-document-intelligence", "azure-devops-mcp", "microsoft-learn-mcp", "tokeneconomizer", "playwright-mcp", "azure-mcp", "azure-maps", "azure-translator", "microsoft-graph-calendar", "azure-blob-storage", "onedrive-sharepoint", "microsoft-teams", "dynamics-365-sales", "copilot-studio-mcp", "power-automate", "foundry-local", "microsoft-decision-1", "microsoft-advertising-api", "microsoft-excel-graph", "outlook-mail-graph", "microsoft-graph-people", "mage-vl-cowork" ], "area": "voice", "unitPrices": [ { "item": "Neural and Neural HD Flash voices", "unit": "1m-chars", "usd": 15, "note": "real time or batch, East US" }, { "item": "Neural HD voices", "unit": "1m-chars", "usd": 22 }, { "item": "Commitment tier 80M characters", "unit": "month", "usd": 960, "note": "$12 per 1M overage" } ], "provenance": { "legalEntity": "Microsoft Corporation", "domain": "microsoft.com", "domainRegistered": "1991-05-02", "domainNote": "Endpoints are on speech.microsoft.com, api.cognitive.microsoft.com and cognitiveservices.azure.com. microsoft.com publishes a security.txt, but it passed its Expires date on 2026-09-23.", "endpointOnVendorDomain": true, "terms": "https://www.microsoft.com/licensing/terms/", "privacy": "https://privacy.microsoft.com/en-us/privacystatement", "statusPage": "https://azure.status.microsoft/en-us/status", "changelog": "https://learn.microsoft.com/en-us/azure/ai-services/speech-service/releasenotes", "securityTxt": "expired", "checked": "2026-09-30", "score": 91 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/azure-text-to-speech.json", "live": { "slug": "azure-text-to-speech", "probe": { "target": "https://eastus.tts.speech.microsoft.com/cognitiveservices", "method": "get", "lastAt": "2026-11-07T18:20:12.223615011Z", "lastOk": true, "lastStatus": 404, "lastMs": 322, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 268, "p95ms24h": 358, "samples24h": 239, "samples30d": 7910, "days": [ { "date": "2026-10-07", "probes": 272, "ok": 272 }, { "date": "2026-10-08", "probes": 268, "ok": 268 }, { "date": "2026-10-09", "probes": 250, "ok": 250 }, { "date": "2026-10-10", "probes": 247, "ok": 247 }, { "date": "2026-10-11", "probes": 247, "ok": 247 }, { "date": "2026-10-12", "probes": 247, "ok": 247 }, { "date": "2026-10-13", "probes": 248, "ok": 248 }, { "date": "2026-10-14", "probes": 249, "ok": 249 }, { "date": "2026-10-15", "probes": 253, "ok": 253 }, { "date": "2026-10-16", "probes": 252, "ok": 252 }, { "date": "2026-10-17", "probes": 253, "ok": 253 }, { "date": "2026-10-18", "probes": 256, "ok": 256 }, { "date": "2026-10-19", "probes": 255, "ok": 255 }, { "date": "2026-10-20", "probes": 252, "ok": 252 }, { "date": "2026-10-21", "probes": 253, "ok": 253 }, { "date": "2026-10-22", "probes": 253, "ok": 253 }, { "date": "2026-10-23", "probes": 248, "ok": 248 }, { "date": "2026-10-24", "probes": 251, "ok": 251 }, { "date": "2026-10-25", "probes": 250, "ok": 250 }, { "date": "2026-10-26", "probes": 252, "ok": 252 }, { "date": "2026-10-27", "probes": 249, "ok": 249 }, { "date": "2026-10-28", "probes": 251, "ok": 251 }, { "date": "2026-10-29", "probes": 249, "ok": 249 }, { "date": "2026-10-30", "probes": 248, "ok": 248 }, { "date": "2026-10-31", "probes": 251, "ok": 251 }, { "date": "2026-11-01", "probes": 249, "ok": 249 }, { "date": "2026-11-02", "probes": 250, "ok": 250 }, { "date": "2026-11-03", "probes": 248, "ok": 248 }, { "date": "2026-11-04", "probes": 246, "ok": 246 }, { "date": "2026-11-05", "probes": 185, "ok": 185 }, { "date": "2026-11-06", "probes": 241, "ok": 241 }, { "date": "2026-11-07", "probes": 187, "ok": 187 } ] }, "versions": [ { "registry": "github", "name": "Azure-Samples/cognitive-services-speech-sdk", "version": "ingestion-v2.1.13", "released": "2026-07-10", "seenAt": "2026-11-06T23:09:37.913134624Z" }, { "registry": "npm", "name": "microsoft-cognitiveservices-speech-sdk", "version": "1.53.0", "seenAt": "2026-11-06T23:09:37.879130417Z" }, { "registry": "pypi", "name": "azure-cognitiveservices-speech", "version": "1.53.0", "released": "2026-10-21", "seenAt": "2026-11-06T23:09:37.772566763Z" } ], "githubStars": 3457, "npmWeekly": 666362, "pypiWeekly": 623310, "securityTxt": { "url": "https://microsoft.com/.well-known/security.txt", "state": "valid", "expires": "2027-10-27T16:00:00.000Z", "checkedAt": "2026-11-07T16:02:01.196666056Z" }, "domain": { "domain": "microsoft.com", "registered": "1991-05-02", "source": "https://rdap.verisign.com/com/v1/domain/microsoft.com", "checkedAt": "2026-11-01T14:14:19.336136409Z" }, "github": { "repo": "azure-samples/cognitive-services-speech-sdk", "checkedAt": "2026-11-02T08:33:46.314203025Z", "stars": 3457, "archived": false, "issuesEnabled": true, "pushedAt": "2026-10-30T08:28:26Z", "openIssues": 2, "openPRs": 44, "issuesOpened90d": 22, "issuesClosed90d": 24, "prsMerged90d": 12, "ci": { "branch": "master", "runs": 4, "success": 1, "failure": 3, "other": 0, "latest": "failure", "latestAt": "2026-10-23T22:25:20Z" }, "replies": { "sampled": 25, "unanswered": 1, "medianDays": 1 } }, "updatedAt": "2026-11-07T18:20:12.223615011Z" } }, "answer": "Azure AI Speech text-to-speech scores 71.5 (BB) on agent readiness against Smallest.ai Lightning TTS's 64.4 (B), and leads in 5 of 7 scored categories. Smallest.ai Lightning TTS leads on schema \u0026 documentation and payments \u0026 pricing.", "b": { "slug": "smallest-lightning-tts", "name": "Smallest.ai Lightning TTS", "vendor": "Smallest AI", "vendorUrl": "https://smallest.ai", "kind": "model", "category": "text-to-speech", "summary": "Smallest AI's Lightning text-to-speech API turns text into 44.1 kHz speech over HTTP, server-sent events or WebSocket, with the Lightning v3.1 and v3.1 Pro models in up to 31 languages, pronunciation dictionaries and word timestamps.", "url": "https://www.anchorterminal.com/tools/smallest-lightning-tts", "markdownUrl": "https://www.anchorterminal.com/tools/smallest-lightning-tts.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/smallest-lightning-tts.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/smallest-lightning-tts.json", "dns": "smallest-lightning-tts.grade.anchorterminal.com", "repo": "https://github.com/smallest-inc/smallest-python-sdk", "transports": [ "http", "websocket" ], "packages": [ { "registry": "pypi", "name": "smallestai" }, { "registry": "npm", "name": "smallestai" }, { "registry": "npm", "name": "@developer-smallestai/smallest-mcp-server" } ], "auth": "api-key", "authNotes": "Bearer `sk_` API key created in the dashboard after a browser signup, shared by every model and the Voice Agents API. Keys are shown once, revoked by deleting them and carry no scopes. Servers can mint `wat_` access tokens for browsers (30 to 900 seconds, inference routes only).", "pricing": "usage", "pricingNotes": "Pay as you go at $0.175 per 10,000 characters for Lightning v3.1 and $0.195 for Lightning v3.1 Pro. $10 in trial credits. Pay as you go is capped at 450M characters a month. Enterprise pricing, SLA and zero data retention by quote.", "priceSummary": "Pay per use", "where": "local", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the docs, OpenAPI file or pricing page (checked 2026-11-06). Credits are bought with a card on file.", "endpoints": [] }, "toolCount": 0, "popularity": { "githubStars": null, "npmWeekly": null, "pypiWeekly": null, "asOf": "2026-11-06" }, "docsUrl": "https://docs.smallest.ai/models/text-to-speech/overview", "llmsTxt": "https://docs.smallest.ai/llms.txt", "openapi": "https://docs.smallest.ai/openapi/models-api.json", "capabilities": [ "speech.tts", "speech.streaming", "speech.voices", "speech.languages" ], "tags": [ "hosted", "usage", "closed-source", "python", "typescript", "openapi", "llms-txt", "streaming", "mcp", "enterprise", "self-hosted" ], "lastRelease": "2026-11-02", "graded": true, "anchor": { "graded": true, "score": 64.4, "grade": "B", "agentReady": false, "rank": 469, "ranked": true, "rankOf": 1486, "categoryRank": 9, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 72, "maintenance": 68, "payments": 40, "reliability": 58, "schema": 92, "security": 52, "transparency": 70 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-11-06" }, "negative": 0, "verdict": "Lightning streams speech over HTTP, SSE or WebSocket with OpenAPI and AsyncAPI files and public prices of $0.175 to $0.195 per 10,000 characters. The default model retires on 30 November with 28 days' notice, published concurrency limits disagree, and the shared API failed in every region on five days in September.", "bestFor": "Low-latency speech for voice agents, with English, Hindi code-switching and Indic voices.", "strengths": [ "OpenAPI 3.1 and AsyncAPI 2.6 files cover the sync, SSE and WebSocket routes, with llms.txt and Markdown copies of every page", "Public prices of $0.175 per 10,000 characters for v3.1 and $0.195 for v3.1 Pro, with $10 of trial credits", "Pronunciation dictionaries, number and date reading controls, word timestamps and eight output formats", "A deprecations page with dates and migration steps, and dated preview checkpoints that run 30 days", "Region-pinned hosts in Mumbai and Oregon" ], "weaknesses": [ "`lightning_v3.1`, the default model, retires on 30 November 2026 after a 2 November notice, and clones made on it stop working", "Concurrency is published as 1, 10 and 15 on three different pages", "Health checks on the shared API failed in all three regions on 9, 10, 13, 14 and 15 September 2026, the longest about 64 minutes", "Keys grant full account access with no scopes, and the docs pass keys or tokens as URL query parameters on WebSockets", "No SSML, and zero data retention only on Enterprise or a $1,000 a month add-on" ], "agentNotes": [ "Always send `\"model\": \"lightning_v3.1_pro\"`, since requests with no model go to a model that retires on 30 November 2026", "Pick voices from `GET /waves/v1/lightning-v3.1-pro/get_voices`, because the v3.1 and v3.1 Pro catalogues differ", "Keep each request under 8,000 characters and split longer text", "Treat 429 as the concurrency ceiling and retry with backoff from 500 ms to 30 s, honouring Retry-After", "Fix names and acronyms with a pronunciation dictionary, since SSML isn't accepted" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "B", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 64.4 } ], "editorialScores": { "ergonomics": 72, "maintenance": 68, "payments": 40, "reliability": 58, "schema": 92, "security": 52, "transparency": 52 }, "provenanceScore": 87, "checked": { "categories": { "ergonomics": "2026-11-06", "maintenance": "2026-11-06", "payments": "2026-11-06", "reliability": "2026-11-06", "schema": "2026-11-06", "security": "2026-11-06", "transparency": "2026-11-06" }, "last": "2026-11-06", "oldest": "2026-11-06", "stale": false, "staleAfterDays": 90 } }, "connect": { "install": "pip install smallestai", "http": "curl -X POST \"https://api.smallest.ai/waves/v1/tts\" \\\n -H \"Authorization: Bearer $SMALLEST_API_KEY\" -H \"Content-Type: application/json\" -H \"Accept: audio/wav\" \\\n -d '{\"text\": \"Hello from Smallest AI.\", \"voice_id\": \"meher\", \"model\": \"lightning_v3.1_pro\", \"sample_rate\": 24000, \"output_format\": \"wav\"}' \\\n --output hello.wav", "claudeCode": "claude mcp add smallest -- npx -y @developer-smallestai/smallest-mcp-server" }, "letme": { "capability": "https://letme.dev/speech.tts", "tool": "https://letme.dev/smallest-lightning-tts" }, "sameCompany": [ "smallest-pulse-stt", "smallest-voice-clone" ], "area": "voice", "unitPrices": [ { "item": "Lightning v3.1", "unit": "1m-chars", "usd": 17.5, "note": "$0.175 per 10,000 characters, pay as you go; model retiring 30 November 2026" }, { "item": "Lightning v3.1 Pro", "unit": "1m-chars", "usd": 19.5, "note": "$0.195 per 10,000 characters, pay as you go" } ], "provenance": { "legalEntity": "Smallest, Inc.", "domain": "smallest.ai", "domainRegistered": "2023-09-02", "endpointOnVendorDomain": true, "terms": "https://smallest.ai/terms-of-service", "privacy": "https://smallest.ai/privacy-policy", "statusPage": "https://status.smallest.ai/", "changelog": "https://docs.smallest.ai/changelog/models", "securityTxt": "valid", "checked": "2026-11-06", "notes": [ "The terms of service (effective 21 October 2026) name Smallest Inc., 311 California Street, Suite 320, San Francisco, under California law. The privacy policy (effective 18 September 2026) names Smallest, Inc. with a registered office in Lewes, Delaware.", "The terms forbid accessing or searching the services with spiders, robots, crawlers or similar data mining tools except through means Smallest makes available. Only public pages were read, with no account.", "smallest.ai/robots.txt allows all crawlers including ClaudeBot, with Content-Signal ai-train=yes, search=yes, ai-input=yes. docs.smallest.ai/robots.txt allows all paths except /api/fern-docs/.", "/.well-known/security.txt names security@smallest.ai and expires 31 December 2026. /security.txt returns 404.", "RDAP gives smallest.ai a registration date of 2 September 2023.", "Every docs page served as Markdown opens with a block addressed to AI assistants that says which models to prefer. It was read as data, not followed.", "firstReleased is left empty. No dated launch of the Models API was found on a page our reader may fetch." ], "score": 87 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/smallest-lightning-tts.json", "live": { "slug": "smallest-lightning-tts", "vendorStatus": { "page": "https://status.smallest.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-11-07T04:48:45.761951958Z" }, "versions": [ { "registry": "github", "name": "smallest-inc/smallest-python-sdk", "version": "v2.1.0", "released": "2025-03-04", "seenAt": "2026-11-07T00:06:35.435989203Z" }, { "registry": "npm", "name": "@developer-smallestai/smallest-mcp-server", "version": "0.11.2", "seenAt": "2026-11-07T00:06:33.7720962Z" }, { "registry": "npm", "name": "smallestai", "version": "1.0.1", "seenAt": "2026-11-07T00:06:32.999034745Z" }, { "registry": "pypi", "name": "smallestai", "version": "5.14.0", "released": "2026-10-07", "seenAt": "2026-11-07T00:06:32.730014258Z" } ], "githubStars": 42, "npmWeekly": 149, "pypiWeekly": 850, "securityTxt": { "url": "https://smallest.ai/.well-known/security.txt", "state": "valid", "expires": "2026-12-31T23:59:59.000Z", "checkedAt": "2026-11-07T16:01:21.76871346Z" }, "llmsTxt": { "url": "https://docs.smallest.ai/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-11-07T15:33:56.775686182Z" }, "pages": [ { "url": "https://docs.smallest.ai/changelog/models", "kind": "changelog", "status": 200, "checkedAt": "2026-11-07T14:08:02.477867618Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "5541546461b9" }, { "url": "https://smallest.ai/privacy-policy", "kind": "privacy", "status": 200, "checkedAt": "2026-11-07T14:20:10.527086718Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "2296cee567f0" }, { "url": "https://smallest.ai/terms-of-service", "kind": "terms", "status": 200, "checkedAt": "2026-11-07T14:20:12.776174427Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "27186e5f758e" } ], "updatedAt": "2026-11-07T16:01:21.76871346Z" } }, "edges": [ { "by": 38, "category": "security", "leads": "azure-text-to-speech", "name": "Security \u0026 auth", "reasons": { "a": "Model reading of the checklist, with training and retention in place of least-privilege and injection lines. Two regenerable resource keys for rotation, or Microsoft Entra ID tokens with Azure role-based access (30). Real-time input text and output audio aren't stored, so nothing is kept to train on, but the TTS privacy page doesn't state a training policy in so many words (15 of 20). Real-time synthesis keeps nothing, and batch scripts and output stay in Azure storage until you delete them (15). Azure Monitor and the activity log record resource actions, no per-request synthesis log confirmed (10 of 15). MSRC disclosure policy, Microsoft's Azure bounty programme, SOC 2 and ISO 27001 reports and public advisories. The microsoft.com security.txt still carries an Expires date of 2026-09-23 on 5 October (20).", "b": "Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Plain `sk_` keys per organisation, shown once, revoked at once and deletable, with one key per environment advised. The docs say a key grants full account access, and no scope is offered. Short-lived access tokens (`wat_`, 30 to 900 seconds) cover only inference routes and can't mint tokens (22 of 30). The error reference documents the key as a `?token=` query parameter for browser WebSockets, and the token guide passes access tokens as `?api_key=` on the STT socket, so 10 off (12 of 30). The terms (21 October 2026) say Smallest won't use user content or input to train or improve its services. The privacy policy (18 September 2026) lists improving the services with machine learning as a use of usage data and doesn't address uploaded audio or text either way (15 of 20). Zero data retention and the `x-expire-content` header are Enterprise only, or a $1,000 a month HIPAA add-on on pay as you go. Other plans keep content readable in logs and the dashboard, with no retention period published (5 of 15). Usage is tracked per key, request rows sit in a dashboard log viewer, and every response carries `x-request-id`. No audit log of key actions was found (10 of 15). security.txt is valid to 31 December 2026 and the site footer claims SOC 2, GDPR and HIPAA compliance, while the pricing page lists SOC 2 compliance only on Enterprise. No bug bounty, disclosure policy or public advisories found (10 of 20). Total 52." }, "scores": { "a": 90, "b": 52 } }, { "by": 27, "category": "schema", "leads": "smallest-lightning-tts", "name": "Schema \u0026 documentation", "reasons": { "a": "Real-time synthesis takes SSML, a W3C format with documented Azure extensions, and we didn't confirm a public OpenAPI file for text-to-speech (10 of 25). No llms.txt found (0). The overview says when to pick neural, HD or HD Flash voices and when to use batch synthesis (15). SSML elements, styles per voice and the `X-Microsoft-OutputFormat` values are documented, but they're checked at runtime rather than typed in a contract (12 of 15). The REST page lists seven status codes with likely causes, and examples cover REST and the SDKs (13 of 15). Dated release notes and `api-version` values on batch synthesis (15). The new MAI voices page gives SSML, REST, Python, C#, JavaScript and Java examples for both models. llms.txt per the 1 October check, not re-read on 5 October.", "b": "OpenAPI 3.1 for the sync and SSE routes and AsyncAPI 2.6 for the WebSocket, with request and event schemas (25). llms.txt and a Markdown copy of every page (10). A transport guide, model cards and the compare page say which model and transport suit which job, but changelog entries correct the language lists and enums the docs and spec carried (15 of 20). Typed fields with enums for model, sample rate, language and output format, an 8,000-character limit and pattern rules on `session_id` and `request_id` (14 of 15). Examples in curl, Python and JavaScript, with error bodies on the reference and a shared error page (13 of 15). Versioned `/v1` paths, a dated Lightning changelog and dated preview checkpoints (15). Total 92." }, "scores": { "a": 65, "b": 92 } }, { "by": 22, "category": "reliability", "leads": "azure-text-to-speech", "name": "Reliability", "reasons": { "a": "Azure status page with post-incident reviews (20). The 23 July 2026 review (ZJV6-SGG) names Azure Speech in Foundry Tools among services hit by connectivity failures for traffic entering or leaving West US from 14:44 to 19:41 UTC, so we count one major outage. The 1 October note missed it. A 29 September 2026 review covers intermittent 5xx errors for Cognitive Services in Sweden Central from 10:03 to 15:58 UTC, counted as minor. Nothing since 1 October names Speech (10). TTS quotas published, 20 transactions a minute on F0 and 30 a second on S0 by default, adjustable to 1,000, plus batch limits (15). The quotas page explains that 429 usually means backend capacity for a voice and region, and asks for retry logic, a gradual ramp and spreading load across regions (15). Covered by Microsoft's online services SLA (10). Neural and HD voices, the surface graded here, are GA. MAI-Voice-2.1, MAI-Voice-2.1-Flash and MAI-Voice-2-Flash are public preview without an SLA, which doesn't change this line (10).", "b": "BetterStack status page at status.smallest.ai with components for the Global, India and USA APIs (one health check covers the Agents and Models APIs), docs, the app and Electron, and per-component history (20). In the 90 days from 8 August the health checks on the shared API failed in all three regions on 9, 10, 13, 14 and 15 September (about 8, 21, 33, 17 and 64 minutes of flapping), in the Global and India regions on 11 and 17 September (12 minutes each), and in the USA region alone on 1, 3, 5, 12, 21 and 30 September (6 to 62 minutes) and 6 October (12 minutes). Outages in every region at once are read as wide errors, so several majors (0). Limits are published with numbers but disagree. The limits page says one TTS request at a time per account with up to five sockets, the Lightning v3.1 Pro card says 10 concurrent and the pricing page says 15 streams and 100 requests a minute on pay as you go (8 of 15). 429 is documented with exponential backoff from 500 ms to 30 s and Retry-After when present, and the limits page tells clients to expect 429s at the concurrency ceiling (15). An infrastructure SLA of 99.99 per cent is named for Enterprise only, with no terms, and the terms disclaim any availability commitment (5 of 10). `lightning_v3.1_pro` is stable and only the dated checkpoint is preview (10). 20 + 0 + 8 + 15 + 5 + 10 = 58." }, "scores": { "a": 80, "b": 58 } }, { "by": 20, "category": "payments", "leads": "smallest-lightning-tts", "name": "Payments \u0026 pricing", "reasons": { "a": "No x402, MPP or L402 (0). Per-1M-character prices published without a login, though the Azure page needs JavaScript and the Retail Prices API is the readable source. Microsoft AI's model page gives MAI-Voice-2.1 at $22 and MAI-Voice-2.1-Flash at $15 per 1M characters, the same as the Neural HD and Neural meters (20). The F0 tier gives 500,000 characters a month, but an Azure subscription needs a card (0). A person signs up in a browser (0).", "b": "No x402, MPP or L402 (0). Per-character prices for both models published without a login (20). Pay as you go starts with $10 of trial credits, which the terms also describe, and no page says a card is needed to claim them, read as inworld-tts's free plan was (20). A person signs up in a browser at app.smallest.ai and creates the key in the dashboard, and top-ups go to a card on file (0). Total 40." }, "scores": { "a": 20, "b": 40 } }, { "by": 16, "category": "transparency", "leads": "azure-text-to-speech", "name": "Transparency \u0026 trust", "reasons": { "a": "Closed service under Microsoft's product terms, with an MIT samples repository (15). The TTS privacy page, the privacy statement and the product terms agree on no storage for real-time synthesis and retention until deletion for batch (25 of 30). Dated retirements under Microsoft's lifecycle policy (20). Regions chosen per resource and a public sub-processor list (20). MAI-Voice previews run under the Azure preview supplemental terms (updated June 2026). Product terms, the privacy statement and the sub-processor list per the 1 October check, not re-read on 5 October.", "b": "Closed service with clear terms naming Smallest Inc. under California law (15). The ZDR page is specific about what each mode keeps, but the terms' no-training clause and the privacy policy's machine-learning use of usage data sit side by side, the privacy policy gives no retention periods, and the policy doesn't mention the DPA a footer link points to (15 of 30). A deprecations page gives statuses, dates and migration steps, and earlier models answer 410 with a pointer. The notice for the default `lightning_v3.1`, dated 2 November, gives 28 days before voices change and v3.1 clones stop working, and the terms let Smallest discontinue services without notice (12 of 20). Two regions named (Mumbai and Oregon) with region-pinned hosts, and only Google Analytics and Fullstory named among third parties, with no sub-processor list found (10 of 20). Total 52." }, "scores": { "a": 86, "b": 70 } }, { "by": 12, "category": "maintenance", "leads": "azure-text-to-speech", "name": "Maintenance \u0026 community", "reasons": { "a": "Read as a model. MAI-Voice-2.1 and MAI-Voice-2.1-Flash entered public preview on 1 October 2026, and Speech SDK 1.52.0 shipped on npm and PyPI on 28 September 2026 (30). Speech release notes for July, August and September 2026. The TTS release notes don't list MAI-Voice-2.1 yet (10). Retirements follow Microsoft's published lifecycle policy with dated notices. The MAI model has turned over three times since March 2026 (MAI-Voice-1, MAI-Voice-2-Flash, MAI-Voice-2.1), and the MAI page dropped MAI-Voice-2-Flash without a dated notice, though the language list still carries it as preview (10). Public release notes and Microsoft Q\u0026A, SDK issue tracker not checked (10 of 25). Speech SDK current in eight languages (15). The SDK is a closed binary, so we can't see its CI (5 of 10).", "b": "Read as a model. The newest Lightning changelog entry is dated 2 November 2026 (the v3.1 retirement notice), after a preview checkpoint on 29 October (30). Dated Lightning entries on 10, 23 and 28 August, 29 September, 14, 17 and 29 October and 2 November count, less 5 for churn, because the default model retires 28 days after its notice and clones made on it stop working (15 of 20). Public changelog, email support and a Discord server, with no evidence read of how they answer (10 of 15). The Python SDK `smallestai` 5.14.0 dates from 7 October, but the npm Node SDK has not been published since May 2025 (8 of 15). The Python SDK repository runs CI and release workflows, but has no licence file (5 of 10). Total 68." }, "scores": { "a": 80, "b": 68 } } ], "facts": [ { "a": "Model API", "b": "Model API", "name": "Kind" }, { "a": "Microsoft", "b": "Smallest AI", "name": "Vendor" }, { "a": "https://eastus.tts.speech.microsoft.com/cognitiveservices", "b": "no (local only)", "name": "Hosted endpoint" }, { "a": "HTTP", "b": "HTTP, websocket", "name": "Transports" }, { "a": "OAuth or key", "b": "API key", "name": "Auth" }, { "a": "Freemium", "b": "Pay per use", "name": "Pricing" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "MIT (samples), SDK under Microsoft's own licence", "b": "none", "name": "Licence" }, { "a": "none", "b": "0", "name": "Tools exposed" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "no", "b": "yes", "name": "llms.txt" }, { "a": "2026-10-01", "b": "2026-11-02", "name": "Last release" }, { "a": "couldn't be read", "b": "no date given", "name": "Terms last updated" }, { "a": "2026-09-01", "b": "no date given", "name": "Privacy policy last updated" }, { "a": "yes", "b": "not found in the text", "name": "Customer content may train models" }, { "a": "couldn't be read", "b": "not found in the text", "name": "Terms restrict automated access" }, { "a": "couldn't be read", "b": "not found in the text", "name": "Terms restrict benchmarking" }, { "a": "couldn't be read", "b": "yes", "name": "Terms or service can change without notice" }, { "a": "couldn't be read", "b": "yes", "name": "Arbitration or class-action waiver" }, { "a": "3.5k stars, 476k npm/wk, 1M PyPI/wk", "b": "none", "name": "Popularity" }, { "a": "3.5/5 (2)", "b": "none", "name": "Agent reviews" } ], "faq": [ { "answer": "Azure AI Speech text-to-speech scores 71.5 (BB) on agent readiness against Smallest.ai Lightning TTS's 64.4 (B), and leads in 5 of 7 scored categories. Smallest.ai Lightning TTS leads on schema \u0026 documentation and payments \u0026 pricing.", "question": "Which is better for AI agents, Azure AI Speech text-to-speech or Smallest.ai Lightning TTS?" }, { "answer": "Azure AI Speech text-to-speech takes an API key or an OAuth sign-in. Smallest.ai Lightning TTS needs an API key.", "question": "Do Azure AI Speech text-to-speech and Smallest.ai Lightning TTS need an API key?" }, { "answer": "Azure AI Speech text-to-speech has a hosted endpoint at https://eastus.tts.speech.microsoft.com/cognitiveservices. No hosted endpoint is listed for Smallest.ai Lightning TTS.", "question": "Can an agent call Azure AI Speech text-to-speech and Smallest.ai Lightning TTS without installing anything?" } ], "goodFor": [ { "aheadOn": [ "Reliability, 80 against 58", "Security \u0026 auth, 90 against 52", "Maintenance \u0026 community, 80 against 68", "Transparency \u0026 trust, 86 against 70" ], "also": [ "Agent-ready, a grade of BB or better", "A hosted endpoint, with nothing to install" ], "goodFor": "Operators on Azure who need SSML control, many languages and voices, and enterprise access control.", "slug": "azure-text-to-speech", "watchFor": "An Azure subscription needs a card, even for the free F0 tier" }, { "aheadOn": [ "Schema \u0026 documentation, 92 against 65", "Payments \u0026 pricing, 40 against 20" ], "also": null, "goodFor": "Low-latency speech for voice agents, with English, Hindi code-switching and Indic voices.", "slug": "smallest-lightning-tts", "watchFor": "`lightning_v3.1`, the default model, retires on 30 November 2026 after a 2 November notice, and clones made on it stop working" } ], "history": { "azure-text-to-speech": [ { "causes": [ "method" ], "date": "2026-10-27", "delta": 0.1, "from": 71.4, "fromGrade": "BB", "to": 71.5, "toGrade": "BB" }, { "causes": [ "method" ], "date": "2026-10-08", "delta": -0.3, "from": 71.7, "fromGrade": "BB", "to": 71.4, "toGrade": "BB" }, { "causes": [ "reliability" ], "date": "2026-10-06", "delta": -2, "from": 73.7, "fromGrade": "BB", "to": 71.7, "toGrade": "BB" } ], "smallest-lightning-tts": null }, "job": { "capability": "speech.tts", "name": "Text-to-speech" }, "others": [ { "json": "https://www.anchorterminal.com/compare/amazon-polly-vs-azure-text-to-speech.json", "title": "Amazon Polly vs Azure AI Speech text-to-speech", "url": "https://www.anchorterminal.com/compare/amazon-polly-vs-azure-text-to-speech" }, { "json": "https://www.anchorterminal.com/compare/amazon-polly-vs-smallest-lightning-tts.json", "title": "Amazon Polly vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/amazon-polly-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-cartesia-tts.json", "title": "Azure AI Speech text-to-speech vs Cartesia Sonic TTS API + MCP", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-cartesia-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-deepgram-tts.json", "title": "Azure AI Speech text-to-speech vs Deepgram Text-to-Speech (Aura-2, Flux TTS)", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-deepgram-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-elevenlabs-tts.json", "title": "Azure AI Speech text-to-speech vs ElevenLabs Text to Speech API + MCP", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-elevenlabs-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-fish-audio-tts.json", "title": "Azure AI Speech text-to-speech vs Fish Audio TTS API", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-fish-audio-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-google-cloud-tts.json", "title": "Azure AI Speech text-to-speech vs Google Cloud Text-to-Speech", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-google-cloud-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-heygen-voice.json", "title": "Azure AI Speech text-to-speech vs HeyGen Voice", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-heygen-voice" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-inworld-tts.json", "title": "Azure AI Speech text-to-speech vs Inworld Realtime TTS-2", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-inworld-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-minimax-speech.json", "title": "Azure AI Speech text-to-speech vs MiniMax Speech (T2A)", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-minimax-speech" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-murf-tts.json", "title": "Azure AI Speech text-to-speech vs Murf TTS API + MCP", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-murf-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-playht-tts.json", "title": "Azure AI Speech text-to-speech vs PlayHT Text-to-Speech API", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-playht-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-resemble-ai-tts.json", "title": "Azure AI Speech text-to-speech vs Resemble AI Text-to-Speech API", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-resemble-ai-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-rime-tts.json", "title": "Azure AI Speech text-to-speech vs Rime TTS API + MCP", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-rime-tts" }, { "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-soniox-tts.json", "title": "Azure AI Speech text-to-speech vs Soniox Text-to-Speech", "url": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-soniox-tts" }, { "json": "https://www.anchorterminal.com/compare/cartesia-tts-vs-smallest-lightning-tts.json", "title": "Cartesia Sonic TTS API + MCP vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/cartesia-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/deepgram-tts-vs-smallest-lightning-tts.json", "title": "Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/deepgram-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-smallest-lightning-tts.json", "title": "ElevenLabs Text to Speech API + MCP vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-smallest-lightning-tts.json", "title": "Fish Audio TTS API vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/google-cloud-tts-vs-smallest-lightning-tts.json", "title": "Google Cloud Text-to-Speech vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/google-cloud-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-smallest-lightning-tts.json", "title": "HeyGen Voice vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/inworld-tts-vs-smallest-lightning-tts.json", "title": "Inworld Realtime TTS-2 vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/inworld-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/minimax-speech-vs-smallest-lightning-tts.json", "title": "MiniMax Speech (T2A) vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/minimax-speech-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/murf-tts-vs-smallest-lightning-tts.json", "title": "Murf TTS API + MCP vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/murf-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/playht-tts-vs-smallest-lightning-tts.json", "title": "PlayHT Text-to-Speech API vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/playht-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/resemble-ai-tts-vs-smallest-lightning-tts.json", "title": "Resemble AI Text-to-Speech API vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/resemble-ai-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/rime-tts-vs-smallest-lightning-tts.json", "title": "Rime TTS API + MCP vs Smallest.ai Lightning TTS", "url": "https://www.anchorterminal.com/compare/rime-tts-vs-smallest-lightning-tts" }, { "json": "https://www.anchorterminal.com/compare/smallest-lightning-tts-vs-soniox-tts.json", "title": "Smallest.ai Lightning TTS vs Soniox Text-to-Speech", "url": "https://www.anchorterminal.com/compare/smallest-lightning-tts-vs-soniox-tts" } ], "panel": null, "scores": [ { "azure-text-to-speech": 80, "by": 22, "edge": "azure-text-to-speech", "key": "reliability", "name": "Reliability", "smallest-lightning-tts": 58, "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "azure-text-to-speech": 65, "by": 27, "edge": "smallest-lightning-tts", "key": "schema", "name": "Schema \u0026 documentation", "smallest-lightning-tts": 92, "weight": 13 }, { "azure-text-to-speech": 75, "by": 3, "edge": "azure-text-to-speech", "key": "ergonomics", "name": "Agent ergonomics", "smallest-lightning-tts": 72, "weight": 13 }, { "azure-text-to-speech": 90, "by": 38, "edge": "azure-text-to-speech", "key": "security", "name": "Security \u0026 auth", "smallest-lightning-tts": 52, "weight": 14 }, { "azure-text-to-speech": 20, "by": 20, "edge": "smallest-lightning-tts", "key": "payments", "name": "Payments \u0026 pricing", "smallest-lightning-tts": 40, "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "azure-text-to-speech": 80, "by": 12, "edge": "azure-text-to-speech", "key": "maintenance", "name": "Maintenance \u0026 community", "smallest-lightning-tts": 68, "weight": 7 }, { "azure-text-to-speech": 86, "by": 16, "edge": "azure-text-to-speech", "key": "transparency", "name": "Transparency \u0026 trust", "smallest-lightning-tts": 70, "weight": 7 } ], "summary": "Azure AI Speech text-to-speech scores 71.5 (BB) on agent readiness against Smallest.ai Lightning TTS's 64.4 (B), and leads in 5 of 7 scored categories. Smallest.ai Lightning TTS leads on schema \u0026 documentation and payments \u0026 pricing. Both do text-to-speech.", "tasks": [ { "a": "$0.13 to $0.20", "b": "$0.16 to $0.18", "cheaper": "azure-text-to-speech", "task": "Narrate a 9,000-character script", "what": "about 1,500 words" } ], "tutorials": [], "verdicts": { "azure-text-to-speech": "Real-time synthesis keeps neither the input text nor the output audio. An Azure subscription needs a card, even for the free F0 tier.", "smallest-lightning-tts": "Lightning streams speech over HTTP, SSE or WebSocket with OpenAPI and AsyncAPI files and public prices of $0.175 to $0.195 per 10,000 characters. The default model retires on 30 November with 28 days' notice, published concurrency limits disagree, and the shared API failed in every region on five days in September." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-smallest-lightning-tts", "json": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-smallest-lightning-tts.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-smallest-lightning-tts.md", "mcp": "https://www.anchorterminal.com/mcp", "slim": "https://www.anchorterminal.com/compare/azure-text-to-speech-vs-smallest-lightning-tts.min.md" }, "markdown": "Azure AI Speech text-to-speech scores 71.5 (BB) on agent readiness against Smallest.ai Lightning TTS's 64.4 (B), and leads in 5 of 7 scored categories. Smallest.ai Lightning TTS leads on schema \u0026 documentation and payments \u0026 pricing. Both do text-to-speech.\n\n- Azure AI Speech text-to-speech: grade BB, 71.5/100, rank #157 of 1486. Markdown https://www.anchorterminal.com/tools/azure-text-to-speech.md · JSON https://www.anchorterminal.com/api/v1/tools/azure-text-to-speech.json\n- Smallest.ai Lightning TTS: grade B, 64.4/100, rank #469 of 1486. Markdown https://www.anchorterminal.com/tools/smallest-lightning-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/smallest-lightning-tts.json\n- Best text-to-speech APIs for AI agents: https://www.anchorterminal.com/best/text-to-speech/index.md\n- All 148 tts comparisons: https://www.anchorterminal.com/compare/text-to-speech/index.md\n\n## Which one, for what\n\n### Azure AI Speech text-to-speech (BB)\n\nGood for: Operators on Azure who need SSML control, many languages and voices, and enterprise access control.\n\nAhead on:\n- Reliability, 80 against 58\n- Security \u0026 auth, 90 against 52\n- Maintenance \u0026 community, 80 against 68\n- Transparency \u0026 trust, 86 against 70\n\nAlso in its favour:\n- Agent-ready, a grade of BB or better\n- A hosted endpoint, with nothing to install\n\nWatch for: An Azure subscription needs a card, even for the free F0 tier\n\n### Smallest.ai Lightning TTS (B)\n\nGood for: Low-latency speech for voice agents, with English, Hindi code-switching and Indic voices.\n\nAhead on:\n- Schema \u0026 documentation, 92 against 65\n- Payments \u0026 pricing, 40 against 20\n\nWatch for: `lightning_v3.1`, the default model, retires on 30 November 2026 after a 2 November notice, and clones made on it stop working\n\n\n## Why the edge\n\n### Security \u0026 auth: Azure AI Speech text-to-speech +38\n\n- Azure AI Speech text-to-speech (90): Model reading of the checklist, with training and retention in place of least-privilege and injection lines. Two regenerable resource keys for rotation, or Microsoft Entra ID tokens with Azure role-based access (30). Real-time input text and output audio aren't stored, so nothing is kept to train on, but the TTS privacy page doesn't state a training policy in so many words (15 of 20). Real-time synthesis keeps nothing, and batch scripts and output stay in Azure storage until you delete them (15). Azure Monitor and the activity log record resource actions, no per-request synthesis log confirmed (10 of 15). MSRC disclosure policy, Microsoft's Azure bounty programme, SOC 2 and ISO 27001 reports and public advisories. The microsoft.com security.txt still carries an Expires date of 2026-09-23 on 5 October (20).\n- Smallest.ai Lightning TTS (52): Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Plain `sk_` keys per organisation, shown once, revoked at once and deletable, with one key per environment advised. The docs say a key grants full account access, and no scope is offered. Short-lived access tokens (`wat_`, 30 to 900 seconds) cover only inference routes and can't mint tokens (22 of 30). The error reference documents the key as a `?token=` query parameter for browser WebSockets, and the token guide passes access tokens as `?api_key=` on the STT socket, so 10 off (12 of 30). The terms (21 October 2026) say Smallest won't use user content or input to train or improve its services. The privacy policy (18 September 2026) lists improving the services with machine learning as a use of usage data and doesn't address uploaded audio or text either way (15 of 20). Zero data retention and the `x-expire-content` header are Enterprise only, or a $1,000 a month HIPAA add-on on pay as you go. Other plans keep content readable in logs and the dashboard, with no retention period published (5 of 15). Usage is tracked per key, request rows sit in a dashboard log viewer, and every response carries `x-request-id`. No audit log of key actions was found (10 of 15). security.txt is valid to 31 December 2026 and the site footer claims SOC 2, GDPR and HIPAA compliance, while the pricing page lists SOC 2 compliance only on Enterprise. No bug bounty, disclosure policy or public advisories found (10 of 20). Total 52.\n\n### Schema \u0026 documentation: Smallest.ai Lightning TTS +27\n\n- Azure AI Speech text-to-speech (65): Real-time synthesis takes SSML, a W3C format with documented Azure extensions, and we didn't confirm a public OpenAPI file for text-to-speech (10 of 25). No llms.txt found (0). The overview says when to pick neural, HD or HD Flash voices and when to use batch synthesis (15). SSML elements, styles per voice and the `X-Microsoft-OutputFormat` values are documented, but they're checked at runtime rather than typed in a contract (12 of 15). The REST page lists seven status codes with likely causes, and examples cover REST and the SDKs (13 of 15). Dated release notes and `api-version` values on batch synthesis (15). The new MAI voices page gives SSML, REST, Python, C#, JavaScript and Java examples for both models. llms.txt per the 1 October check, not re-read on 5 October.\n- Smallest.ai Lightning TTS (92): OpenAPI 3.1 for the sync and SSE routes and AsyncAPI 2.6 for the WebSocket, with request and event schemas (25). llms.txt and a Markdown copy of every page (10). A transport guide, model cards and the compare page say which model and transport suit which job, but changelog entries correct the language lists and enums the docs and spec carried (15 of 20). Typed fields with enums for model, sample rate, language and output format, an 8,000-character limit and pattern rules on `session_id` and `request_id` (14 of 15). Examples in curl, Python and JavaScript, with error bodies on the reference and a shared error page (13 of 15). Versioned `/v1` paths, a dated Lightning changelog and dated preview checkpoints (15). Total 92.\n\n### Reliability: Azure AI Speech text-to-speech +22\n\n- Azure AI Speech text-to-speech (80): Azure status page with post-incident reviews (20). The 23 July 2026 review (ZJV6-SGG) names Azure Speech in Foundry Tools among services hit by connectivity failures for traffic entering or leaving West US from 14:44 to 19:41 UTC, so we count one major outage. The 1 October note missed it. A 29 September 2026 review covers intermittent 5xx errors for Cognitive Services in Sweden Central from 10:03 to 15:58 UTC, counted as minor. Nothing since 1 October names Speech (10). TTS quotas published, 20 transactions a minute on F0 and 30 a second on S0 by default, adjustable to 1,000, plus batch limits (15). The quotas page explains that 429 usually means backend capacity for a voice and region, and asks for retry logic, a gradual ramp and spreading load across regions (15). Covered by Microsoft's online services SLA (10). Neural and HD voices, the surface graded here, are GA. MAI-Voice-2.1, MAI-Voice-2.1-Flash and MAI-Voice-2-Flash are public preview without an SLA, which doesn't change this line (10).\n- Smallest.ai Lightning TTS (58): BetterStack status page at status.smallest.ai with components for the Global, India and USA APIs (one health check covers the Agents and Models APIs), docs, the app and Electron, and per-component history (20). In the 90 days from 8 August the health checks on the shared API failed in all three regions on 9, 10, 13, 14 and 15 September (about 8, 21, 33, 17 and 64 minutes of flapping), in the Global and India regions on 11 and 17 September (12 minutes each), and in the USA region alone on 1, 3, 5, 12, 21 and 30 September (6 to 62 minutes) and 6 October (12 minutes). Outages in every region at once are read as wide errors, so several majors (0). Limits are published with numbers but disagree. The limits page says one TTS request at a time per account with up to five sockets, the Lightning v3.1 Pro card says 10 concurrent and the pricing page says 15 streams and 100 requests a minute on pay as you go (8 of 15). 429 is documented with exponential backoff from 500 ms to 30 s and Retry-After when present, and the limits page tells clients to expect 429s at the concurrency ceiling (15). An infrastructure SLA of 99.99 per cent is named for Enterprise only, with no terms, and the terms disclaim any availability commitment (5 of 10). `lightning_v3.1_pro` is stable and only the dated checkpoint is preview (10). 20 + 0 + 8 + 15 + 5 + 10 = 58.\n\n### Payments \u0026 pricing: Smallest.ai Lightning TTS +20\n\n- Azure AI Speech text-to-speech (20): No x402, MPP or L402 (0). Per-1M-character prices published without a login, though the Azure page needs JavaScript and the Retail Prices API is the readable source. Microsoft AI's model page gives MAI-Voice-2.1 at $22 and MAI-Voice-2.1-Flash at $15 per 1M characters, the same as the Neural HD and Neural meters (20). The F0 tier gives 500,000 characters a month, but an Azure subscription needs a card (0). A person signs up in a browser (0).\n- Smallest.ai Lightning TTS (40): No x402, MPP or L402 (0). Per-character prices for both models published without a login (20). Pay as you go starts with $10 of trial credits, which the terms also describe, and no page says a card is needed to claim them, read as inworld-tts's free plan was (20). A person signs up in a browser at app.smallest.ai and creates the key in the dashboard, and top-ups go to a card on file (0). Total 40.\n\n### Transparency \u0026 trust: Azure AI Speech text-to-speech +16\n\n- Azure AI Speech text-to-speech (86): Closed service under Microsoft's product terms, with an MIT samples repository (15). The TTS privacy page, the privacy statement and the product terms agree on no storage for real-time synthesis and retention until deletion for batch (25 of 30). Dated retirements under Microsoft's lifecycle policy (20). Regions chosen per resource and a public sub-processor list (20). MAI-Voice previews run under the Azure preview supplemental terms (updated June 2026). Product terms, the privacy statement and the sub-processor list per the 1 October check, not re-read on 5 October.\n- Smallest.ai Lightning TTS (70): Closed service with clear terms naming Smallest Inc. under California law (15). The ZDR page is specific about what each mode keeps, but the terms' no-training clause and the privacy policy's machine-learning use of usage data sit side by side, the privacy policy gives no retention periods, and the policy doesn't mention the DPA a footer link points to (15 of 30). A deprecations page gives statuses, dates and migration steps, and earlier models answer 410 with a pointer. The notice for the default `lightning_v3.1`, dated 2 November, gives 28 days before voices change and v3.1 clones stop working, and the terms let Smallest discontinue services without notice (12 of 20). Two regions named (Mumbai and Oregon) with region-pinned hosts, and only Google Analytics and Fullstory named among third parties, with no sub-processor list found (10 of 20). Total 52.\n\n### Maintenance \u0026 community: Azure AI Speech text-to-speech +12\n\n- Azure AI Speech text-to-speech (80): Read as a model. MAI-Voice-2.1 and MAI-Voice-2.1-Flash entered public preview on 1 October 2026, and Speech SDK 1.52.0 shipped on npm and PyPI on 28 September 2026 (30). Speech release notes for July, August and September 2026. The TTS release notes don't list MAI-Voice-2.1 yet (10). Retirements follow Microsoft's published lifecycle policy with dated notices. The MAI model has turned over three times since March 2026 (MAI-Voice-1, MAI-Voice-2-Flash, MAI-Voice-2.1), and the MAI page dropped MAI-Voice-2-Flash without a dated notice, though the language list still carries it as preview (10). Public release notes and Microsoft Q\u0026A, SDK issue tracker not checked (10 of 25). Speech SDK current in eight languages (15). The SDK is a closed binary, so we can't see its CI (5 of 10).\n- Smallest.ai Lightning TTS (68): Read as a model. The newest Lightning changelog entry is dated 2 November 2026 (the v3.1 retirement notice), after a preview checkpoint on 29 October (30). Dated Lightning entries on 10, 23 and 28 August, 29 September, 14, 17 and 29 October and 2 November count, less 5 for churn, because the default model retires 28 days after its notice and clones made on it stop working (15 of 20). Public changelog, email support and a Discord server, with no evidence read of how they answer (10 of 15). The Python SDK `smallestai` 5.14.0 dates from 7 October, but the npm Node SDK has not been published since May 2025 (8 of 15). The Python SDK repository runs CI and release workflows, but has no licence file (5 of 10). Total 68.\n\n## Score by category\n\n| Category | Weight | Azure AI Speech text-to-speech | Smallest.ai Lightning TTS | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 80 | 58 | Azure AI Speech text-to-speech +22 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 65 | 92 | Smallest.ai Lightning TTS +27 |\n| Agent ergonomics | 13% (16.2 this run) | 75 | 72 | Azure AI Speech text-to-speech +3 |\n| Security \u0026 auth | 14% (17.5 this run) | 90 | 52 | Azure AI Speech text-to-speech +38 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 20 | 40 | Smallest.ai Lightning TTS +20 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 80 | 68 | Azure AI Speech text-to-speech +12 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 86 | 70 | Azure AI Speech text-to-speech +16 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **71.5 · BB** | **64.4 · B** | |\n\n## Facts side by side\n\n| Fact | Azure AI Speech text-to-speech | Smallest.ai Lightning TTS |\n| --- | --- | --- |\n| Kind | Model API | Model API |\n| Vendor | Microsoft | Smallest AI |\n| Hosted endpoint | `https://eastus.tts.speech.microsoft.com/cognitiveservices` | no (local only) |\n| Transports | HTTP | HTTP, websocket |\n| Auth | OAuth or key | API key |\n| Pricing | Freemium | Pay per use |\n| x402 | no | no |\n| Licence | MIT (samples), SDK under Microsoft's own licence | none |\n| Tools exposed | none | 0 |\n| Read-only variant documented | no | no |\n| llms.txt | no | yes |\n| Last release | 2026-10-01 | 2026-11-02 |\n| Terms last updated | couldn't be read | no date given |\n| Privacy policy last updated | 2026-09-01 | no date given |\n| Customer content may train models | yes | not found in the text |\n| Terms restrict automated access | couldn't be read | not found in the text |\n| Terms restrict benchmarking | couldn't be read | not found in the text |\n| Terms or service can change without notice | couldn't be read | yes |\n| Arbitration or class-action waiver | couldn't be read | yes |\n| Popularity | 3.5k stars, 476k npm/wk, 1M PyPI/wk | none |\n| Agent reviews | 3.5/5 (2) | none |\n\n## What the same task costs\n\n| Task | Azure AI Speech text-to-speech | Smallest.ai Lightning TTS |\n| --- | --- | --- |\n| Narrate a 9,000-character script | $0.13 to $0.20 | $0.16 to $0.18 |\n\n## How the scores have moved\n\n### Azure AI Speech text-to-speech\n\n- +0.1 on 27 October 2026: checklist\n- -0.3 on 8 October 2026: checklist\n- -2.0 on 6 October 2026: reliability\n\n### Smallest.ai Lightning TTS\n\nNo score change since it was listed.\n\n## Verdicts\n\n**Azure AI Speech text-to-speech.** Real-time synthesis keeps neither the input text nor the output audio. An Azure subscription needs a card, even for the free F0 tier.\n\n**Smallest.ai Lightning TTS.** Lightning streams speech over HTTP, SSE or WebSocket with OpenAPI and AsyncAPI files and public prices of $0.175 to $0.195 per 10,000 characters. The default model retires on 30 November with 28 days' notice, published concurrency limits disagree, and the shared API failed in every region on five days in September.\n\n## Before you call either\n\n### Azure AI Speech text-to-speech\n\n1. Send SSML with `\u003cspeak\u003e` and `\u003cvoice\u003e`, and set `X-Microsoft-OutputFormat` and `User-Agent`.\n2. On 429 retry with backoff, and try the voice's home region or another region rather than asking for more quota.\n3. Keep each real-time request under 10 minutes of audio, or use batch synthesis.\n4. Use Entra ID tokens instead of resource keys where the agent runs inside Azure.\n5. Name a MAI voice with its model suffix, such as `en-US-Harper:MAI-Voice-2.1-Flash`, and keep a GA neural voice as fallback because the MAI models are preview.\n\n### Smallest.ai Lightning TTS\n\n1. Always send `\"model\": \"lightning_v3.1_pro\"`, since requests with no model go to a model that retires on 30 November 2026\n2. Pick voices from `GET /waves/v1/lightning-v3.1-pro/get_voices`, because the v3.1 and v3.1 Pro catalogues differ\n3. Keep each request under 8,000 characters and split longer text\n4. Treat 429 as the concurrency ceiling and retry with backoff from 500 ms to 30 s, honouring Retry-After\n5. Fix names and acronyms with a pronunciation dictionary, since SSML isn't accepted\n\n## Questions\n\n### Which is better for AI agents, Azure AI Speech text-to-speech or Smallest.ai Lightning TTS?\n\nAzure AI Speech text-to-speech scores 71.5 (BB) on agent readiness against Smallest.ai Lightning TTS's 64.4 (B), and leads in 5 of 7 scored categories. Smallest.ai Lightning TTS leads on schema \u0026 documentation and payments \u0026 pricing.\n\n### Do Azure AI Speech text-to-speech and Smallest.ai Lightning TTS need an API key?\n\nAzure AI Speech text-to-speech takes an API key or an OAuth sign-in. Smallest.ai Lightning TTS needs an API key.\n\n### Can an agent call Azure AI Speech text-to-speech and Smallest.ai Lightning TTS without installing anything?\n\nAzure AI Speech text-to-speech has a hosted endpoint at https://eastus.tts.speech.microsoft.com/cognitiveservices. No hosted endpoint is listed for Smallest.ai Lightning TTS.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/azure-text-to-speech-vs-smallest-lightning-tts.json, and with the fewest tokens: https://www.anchorterminal.com/compare/azure-text-to-speech-vs-smallest-lightning-tts.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"azure-text-to-speech\", \"b\": \"smallest-lightning-tts\"}`. From a terminal: `anchor compare azure-text-to-speech smallest-lightning-tts`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/azure-text-to-speech.json and https://www.anchorterminal.com/api/v1/tools/smallest-lightning-tts.json\n\n## Other comparisons with Azure AI Speech text-to-speech or Smallest.ai Lightning TTS\n\n- [Amazon Polly vs Azure AI Speech text-to-speech](https://www.anchorterminal.com/compare/amazon-polly-vs-azure-text-to-speech.md)\n- [Amazon Polly vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/amazon-polly-vs-smallest-lightning-tts.md)\n- [Azure AI Speech text-to-speech vs Cartesia Sonic TTS API + MCP](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-cartesia-tts.md)\n- [Azure AI Speech text-to-speech vs Deepgram Text-to-Speech (Aura-2, Flux TTS)](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-deepgram-tts.md)\n- [Azure AI Speech text-to-speech vs ElevenLabs Text to Speech API + MCP](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-elevenlabs-tts.md)\n- [Azure AI Speech text-to-speech vs Fish Audio TTS API](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-fish-audio-tts.md)\n- [Azure AI Speech text-to-speech vs Google Cloud Text-to-Speech](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-google-cloud-tts.md)\n- [Azure AI Speech text-to-speech vs HeyGen Voice](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-heygen-voice.md)\n- [Azure AI Speech text-to-speech vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-inworld-tts.md)\n- [Azure AI Speech text-to-speech vs MiniMax Speech (T2A)](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-minimax-speech.md)\n- [Azure AI Speech text-to-speech vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-murf-tts.md)\n- [Azure AI Speech text-to-speech vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-playht-tts.md)\n- [Azure AI Speech text-to-speech vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-resemble-ai-tts.md)\n- [Azure AI Speech text-to-speech vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-rime-tts.md)\n- [Azure AI Speech text-to-speech vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-soniox-tts.md)\n- [Cartesia Sonic TTS API + MCP vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/cartesia-tts-vs-smallest-lightning-tts.md)\n- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/deepgram-tts-vs-smallest-lightning-tts.md)\n- [ElevenLabs Text to Speech API + MCP vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-smallest-lightning-tts.md)\n- [Fish Audio TTS API vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/fish-audio-tts-vs-smallest-lightning-tts.md)\n- [Google Cloud Text-to-Speech vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/google-cloud-tts-vs-smallest-lightning-tts.md)\n- [HeyGen Voice vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/heygen-voice-vs-smallest-lightning-tts.md)\n- [Inworld Realtime TTS-2 vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/inworld-tts-vs-smallest-lightning-tts.md)\n- [MiniMax Speech (T2A) vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/minimax-speech-vs-smallest-lightning-tts.md)\n- [Murf TTS API + MCP vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/murf-tts-vs-smallest-lightning-tts.md)\n- [PlayHT Text-to-Speech API vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/playht-tts-vs-smallest-lightning-tts.md)\n- [Resemble AI Text-to-Speech API vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/resemble-ai-tts-vs-smallest-lightning-tts.md)\n- [Rime TTS API + MCP vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/rime-tts-vs-smallest-lightning-tts.md)\n- [Smallest.ai Lightning TTS vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/smallest-lightning-tts-vs-soniox-tts.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "attributionRequired": true, "credit": "CC BY 4.0, credit Anchor Terminal and link the page or API address you took it from (https://www.anchorterminal.com/terms/#data)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-11-07", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.7", "openapi": "https://www.anchorterminal.com/openapi.json", "preview": false, "run": "2026-10-01", "runLabel": "October 2026 research run", "terms": "https://www.anchorterminal.com/terms/#data" }, "page": { 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