{ "data": { "a": { "slug": "heygen-voice", "name": "HeyGen Voice", "vendor": "HeyGen", "vendorUrl": "https://www.heygen.com", "kind": "model", "category": "text-to-speech", "summary": "HeyGen Voice is HeyGen's in-house text-to-speech model, `heygen-voice-1`, which speaks text in a voice cloned from one recording (instant) or from 20 minutes or more (professional), through HeyGen's v3 API.", "url": "https://www.anchorterminal.com/tools/heygen-voice", "markdownUrl": "https://www.anchorterminal.com/tools/heygen-voice.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/heygen-voice.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/heygen-voice.json", "license": "Closed service under HeyGen's Terms of Service (HeyGen Technology, Inc., last updated 23 July 2026).", "transports": [ "http" ], "remoteUrl": "https://api.heygen.com", "packages": [], "auth": "api-key", "authNotes": "An API key from the HeyGen API dashboard, sent in the X-Api-Key header. Keys can be restricted to read and write scopes, and the speech and voice endpoints need voices:write. The OpenAPI file also accepts an OAuth bearer token, which bills subscription credits. Stripe Projects can provision a key through the operator's Stripe account.", "pricing": "usage", "pricingNotes": "Instant-voice speech is $15 per million submitted characters, charged only on successful requests (OpenAPI description, checked 10 October 2026). Professional speech is 0.6 API credits per generated minute, and each professional voice needs a purchased slot. Instant voices are free to create during the preview. No free API allowance was found.", "priceSummary": "Pay per use", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the developer llms.txt, the OpenAPI file or the HeyGen Voice pages, checked 10 October 2026. Keys are funded by API credit or through Stripe Projects.", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": null, "npmWeekly": null, "pypiWeekly": null, "asOf": "2026-10-10" }, "docsUrl": "https://developers.heygen.com/docs/models/heygen-voice", "llmsTxt": "https://developers.heygen.com/llms.txt", "openapi": "https://developers.heygen.com/openapi/external-api.json", "capabilities": [ "speech.tts", "speech.streaming", "speech.languages", "voice.clone" ], "tags": [ "hosted", "official", "usage-priced", "closed-source", "openapi", "llms-txt", "streaming", "status-page", "soc2", "security-txt", "cli", "agent-skills" ], "graded": true, "anchor": { "graded": true, "score": 71.1, "grade": "BB", "agentReady": true, "rank": 149, "ranked": true, "rankOf": 1243, "categoryRank": 5, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 83, "maintenance": 65, "payments": 30, "reliability": 75, "schema": 94, "security": 69, "transparency": 66 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-10" }, "negative": 0, "verdict": "HeyGen Voice has a typed OpenAPI contract, streaming with character timestamps, and a published price of $15 per million characters for instant voices, with failed requests not charged. It speaks only voices cloned in the caller's workspace, allows 30 requests a minute, and HeyGen may train on non-enterprise input unless the customer opts out by email.", "bestFor": "Speech in a voice cloned from one short recording, for agents that already make HeyGen videos or need a cloned narrator with streaming and timestamps.", "strengths": [ "OpenAPI 3.1 file with enums, ranges, `additionalProperties: false` and per-code errors for every speech and voice endpoint", "Streaming over Server-Sent Events, with optional character-level timestamps", "Instant-voice speech priced at $15 per million characters without a login, and failed or disconnected requests are not charged", "API keys can be restricted to read and write scopes, and the speech endpoints need voices:write", "Instant voices are created from one recording, usually ready within seconds, in 39 base languages" ], "weaknesses": [ "Speaks only voices cloned in the caller's workspace. Stock and designed voices go through a separate endpoint and engines", "30 requests a minute per workspace member on the speech endpoints, on every plan", "Output is a 44.1 kHz mono WAV only, and text is capped at 5,000 characters a request", "HeyGen's privacy policy allows training on user input, with an opt-out by email. Enterprise data is excluded by default", "No official SDK, no free API allowance and no SLA in the terms" ], "agentNotes": [ "Create a voice first with POST /v3/models/audio/voices and `mode`, then poll GET /v3/models/audio/voices/{voice_id} until `status` is ACTIVE before calling speech", "Send `expressiveness_boost` only for instant voices and `seed`, `speed`, `pitch_shift`, `pitch_variance` or `\u003cbreak\u003e` tags only for professional voices. Mixing them returns 400 invalid_parameter", "On the stream, decode and play each base64 WAV part in `part_index` order. Do not concatenate the bytes", "Send an Idempotency-Key when creating a voice, and retry 502, 503 and 504 on speech, which the OpenAPI file marks as safe", "Use POST /v3/voices/speech for stock or designed voices. It is a different engine and price" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 4, "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": 71.1 } ], "editorialScores": { "ergonomics": 83, "maintenance": 65, "payments": 30, "reliability": 75, "schema": 94, "security": 69, "transparency": 52 }, "provenanceScore": 79, "checked": { "categories": { "ergonomics": "2026-10-10", "maintenance": "2026-10-10", "payments": "2026-10-10", "reliability": "2026-10-10", "schema": "2026-10-10", "security": "2026-10-10", "transparency": "2026-10-10" }, "last": "2026-10-10", "lastMoved": "2026-10-27", "oldest": "2026-10-10", "stale": false, "staleAfterDays": 90 } }, "connect": { "http": "curl -X POST \"https://api.heygen.com/v3/models/audio/tts\" \\\n -H \"X-Api-Key: $HEYGEN_API_KEY\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\"model\":\"heygen-voice-1\",\"voice_id\":\"\u003cVOICE_ID\u003e\",\"text\":\"Hello.\",\"language\":\"en\",\"expressiveness_boost\":0.8}'" }, "letme": { "capability": "https://letme.dev/speech.tts", "tool": "https://letme.dev/heygen-voice" }, "area": "voice", "unitPrices": [ { "item": "Instant-voice speech", "unit": "1m-chars", "usd": 15, "note": "Submitted Unicode characters, including spaces. Successful requests only." }, { "item": "Professional-voice speech", "unit": "audio-minute", "usd": 0.6, "note": "0.6 API credits per generated minute. The dollar figure assumes $1 a credit, from the OpenAPI example of 9/60 credit for $0.15." } ], "provenance": { "legalEntity": "HeyGen Technology, Inc.", "domain": "heygen.com", "domainRegistered": "", "endpointOnVendorDomain": true, "terms": "https://www.heygen.com/terms", "privacy": "https://www.heygen.com/privacy", "statusPage": "https://status.heygen.com", "changelog": "https://developers.heygen.com/changelog", "securityTxt": "valid", "checked": "2026-10-10", "notes": [ "security.txt at www.heygen.com/.well-known/security.txt names security@heygen.com and expires on 31 December 2026.", "The privacy policy names HeyGen Technology Inc. in section 1 and HeyGen, Inc. as processor in section 15.", "The status page has components per domain (www, app, api) and none for voice.", "Domain registration date was not checked." ], "score": 79 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/heygen-voice.json", "live": { "slug": "heygen-voice", "probe": { "target": "https://api.heygen.com", "method": "get", "lastAt": "2026-10-31T03:04:00.743994677Z", "lastOk": true, "lastStatus": 404, "lastMs": 286, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 310, "p95ms24h": 442, "samples24h": 249, "samples30d": 5049, "days": [ { "date": "2026-10-10", "probes": 1, "ok": 1 }, { "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": 248, "ok": 248 }, { "date": "2026-10-30", "probes": 249, "ok": 249 }, { "date": "2026-10-31", "probes": 32, "ok": 32 } ] }, "vendorStatus": { "page": "https://status.heygen.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-31T03:04:33.566952939Z" }, "securityTxt": { "url": "https://heygen.com/.well-known/security.txt", "state": "valid", "expires": "2026-12-31T08:00:00Z", "checkedAt": "2026-10-30T15:38:17.525339313Z" }, "llmsTxt": { "url": "https://developers.heygen.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-30T15:07:40.773729094Z" }, "domain": { "domain": "heygen.com", "registered": "2015-10-19", "source": "https://rdap.verisign.com/com/v1/domain/heygen.com", "checkedAt": "2026-10-25T13:53:24.607424117Z" }, "pages": [ { "url": "https://developers.heygen.com/changelog", "kind": "deprecations", "status": 200, "checkedAt": "2026-10-30T05:35:30.585453062Z", "changedAt": "2026-10-28T04:13:07.508060998Z", "fingerprint": "0eae567eaa72" }, { "url": "https://www.heygen.com/privacy", "kind": "privacy", "status": 200, "checkedAt": "2026-10-30T05:56:19.524957344Z", "changedAt": "2026-10-24T02:32:30.835098436Z", "fingerprint": "829927849f6f" }, { "url": "https://www.heygen.com/terms", "kind": "terms", "status": 200, "checkedAt": "2026-10-30T05:56:21.739745589Z", "changedAt": "2026-10-24T02:32:33.190413011Z", "fingerprint": "fbb5f922f20c" } ], "updatedAt": "2026-10-31T03:04:33.566952939Z" } }, "answer": "HeyGen Voice scores 71.1 (BB) on agent readiness against Inworld Realtime TTS-2's 58.3 (C), and leads in 5 of 7 scored categories. Inworld Realtime TTS-2 leads on payments \u0026 pricing.", "b": { "slug": "inworld-tts", "name": "Inworld Realtime TTS-2", "vendor": "Inworld AI", "vendorUrl": "https://inworld.ai", "kind": "model", "category": "text-to-speech", "summary": "Inworld's hosted text-to-speech models, `inworld-tts-2` and `inworld-tts-2-flash`, over REST, HTTP streaming, WebSocket, async jobs and an OpenAI-compatible endpoint. TTS-2 takes bracketed steering, and an opt-in Reasoning step writes the delivery direction itself.", "url": "https://www.anchorterminal.com/tools/inworld-tts", "markdownUrl": "https://www.anchorterminal.com/tools/inworld-tts.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/inworld-tts.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/inworld-tts.json", "license": "Proprietary service under Inworld's Terms of Service. The Node.js SDK `@inworld/tts` and the CLI `@inworld/cli` are MIT on npm", "transports": [ "http", "websocket" ], "remoteUrl": "https://api.inworld.ai", "packages": [ { "registry": "npm", "name": "@inworld/tts" }, { "registry": "pypi", "name": "inworld-tts" }, { "registry": "npm", "name": "@inworld/cli" } ], "auth": "api-key", "authNotes": "Every call sends `Authorization: Basic` with the Base64 `key_id:secret` credential copied from the Portal or printed by the CLI. Keys belong to a workspace, are deleted to revoke, and have write toggles only for the Voice and Router APIs, so no key is limited to TTS. Browser and mobile clients use single-use tokens minted server-side, valid 15 minutes by default.", "pricing": "freemium", "pricingNotes": "TTS-2 costs $25 per million characters on the free On-Demand plan, falling to $20, $17.50, $15 and $12.50 on the $25, $100, $300 and $1,500 monthly plans, and from $5 on Enterprise. TTS-2 Flash runs $15 down to $7. On-Demand includes up to 70 minutes of TTS with no card. Steering tags count as characters, while `synthesisContext` and `reasoningContext` aren't billed. Batch costs 20 per cent less (checked 2026-10-30).", "priceSummary": "$25 / mo", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in llms.txt, the TTS docs, the billing page or the pricing page (checked 2026-10-30). Usage is drawn from prepaid plan credits, card top-ups of at least $10 or auto-reload.", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": null, "npmWeekly": 3632, "pypiWeekly": null, "asOf": "2026-10-30" }, "docsUrl": "https://docs.inworld.ai/tts/tts", "llmsTxt": "https://docs.inworld.ai/llms.txt", "capabilities": [ "speech.tts", "speech.streaming", "speech.voices", "speech.ssml", "speech.languages", "speech.batch", "voice.clone", "voice.design" ], "tags": [ "hosted", "official", "closed-source", "freemium", "free-tier", "no-card", "llms-txt", "streaming", "openai-compatible", "reasoning", "multilingual", "async-jobs", "batch", "typescript", "python", "cli", "mcp", "status-page", "soc2", "enterprise" ], "lastRelease": "2026-10-28", "graded": true, "anchor": { "graded": true, "score": 58.3, "grade": "C", "agentReady": false, "rank": 687, "ranked": true, "rankOf": 1243, "categoryRank": 10, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 68, "maintenance": 68, "payments": 40, "reliability": 62, "schema": 60, "security": 61, "transparency": 63 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-30" }, "negative": -2, "negativeNotes": [ "30 October 2026. Inworld's Realtime TTS-2 page shows Realtime TTS-2 as #1 for voice quality on the Artificial Analysis Speech Arena and says the ranks come from the live arena, not hardcoded. Artificial Analysis's provider-voice leaderboard on the same day put Realtime TTS-2 8th (Elo 1,267) behind Eleven v4 Turbo (1,336). The page also says the table was verified in May 2026. The deduction lapses if the page is corrected or the rank returns. Sources: https://inworld.ai/blog/realtime-tts-2 and https://artificialanalysis.ai/text-to-speech/leaderboard/provider-voice (-2)" ], "verdict": "TTS-2 takes bracketed steering, and opt-in Reasoning writes a delivery direction from the text and up to 600 characters of context, returning it in the response. Per-character prices are public and the free plan needs no card. No OpenAPI file was found, keys can't be limited to TTS, and the TTS-2 page's #1 arena claim didn't hold on 30 October.", "bestFor": "Agents that generate replies or stories at runtime and want delivery chosen from context without writing tags, and for per-message or pre-generated audio.", "strengths": [ "Reasoning returns the direction it applied as `reasoningInstruction`, so an agent can log it and reuse it as an inline tag", "Per-character prices are public, from $25 per million characters for TTS-2 on the free plan to $12.50 on Growth", "REST, HTTP streaming, WebSocket, async jobs and an OpenAI-compatible `/v1/audio/speech` endpoint", "llms.txt, Markdown twins of every page and a keyless docs MCP server at docs.inworld.ai/mcp", "Single-use client tokens, 15 minutes by default, keep the API key off browsers and phones" ], "weaknesses": [ "No OpenAPI or other machine-readable contract was found for the TTS API", "API keys can't be limited to TTS. Write toggles cover only the Voice and Router APIs", "The 28 October model update replaced `inworld-tts-2` in place, with no dated snapshot to pin", "Zero data retention is Enterprise only or a Growth add-on, and the SLA is Enterprise only", "The TTS-2 page claims #1 on the Artificial Analysis Speech Arena, which ranked it 8th on 30 October 2026" ], "agentNotes": [ "Send the copied Base64 credential as-is in `Authorization: Basic`. Don't encode it again.", "Set `modelId` explicitly, because SDK defaults may name deprecated models.", "Keep text under 2,000 UTF-16 units on `/tts/v1/voice` and 4,000 on `voice:stream`, or use an async job.", "Turn on Reasoning with `synthesisContext.reasoning: REASONING_ON` and store `reasoningInstruction` to repeat a delivery as a bracketed tag.", "On 429 or error code 8, back off exponentially with jitter. No Retry-After header is documented." ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 58.3 } ], "editorialScores": { "ergonomics": 68, "maintenance": 68, "payments": 40, "reliability": 62, "schema": 60, "security": 61, "transparency": 51 }, "provenanceScore": 75, "checked": { "categories": { "ergonomics": "2026-10-30", "maintenance": "2026-10-30", "payments": "2026-10-30", "reliability": "2026-10-30", "schema": "2026-10-30", "security": "2026-10-30", "transparency": "2026-10-30" }, "last": "2026-10-30", "oldest": "2026-10-30", "stale": false, "staleAfterDays": 90 } }, "connect": { "install": "npm install @inworld/tts", "http": "curl -X POST https://api.inworld.ai/tts/v1/voice -H \"Authorization: Basic $INWORLD_API_KEY\" -H 'Content-Type: application/json' -d '{\"text\": \"We made it. I honestly did not think we would.\", \"voiceId\": \"Dennis\", \"modelId\": \"inworld-tts-2\", \"synthesisContext\": {\"reasoning\": \"REASONING_ON\"}}'", "claudeCode": "claude mcp add inworld -- inworld mcp" }, "letme": { "capability": "https://letme.dev/speech.tts", "tool": "https://letme.dev/inworld-tts" }, "area": "voice", "unitPrices": [ { "item": "Realtime TTS-2, On-Demand (free plan, pay as you go)", "unit": "1m-chars", "usd": 25, "note": "pricing page, checked 30 October 2026" }, { "item": "Realtime TTS-2 on Growth", "unit": "1m-chars", "usd": 12.5, "note": "$20 on Creator, $17.50 on Builder, $15 on Developer, from $5 on Enterprise" }, { "item": "Realtime TTS-2 Flash, On-Demand", "unit": "1m-chars", "usd": 15, "note": "falls to $7 on Growth" }, { "item": "Creator plan", "unit": "month", "usd": 25, "note": "$25 in credits a month" }, { "item": "Developer plan", "unit": "month", "usd": 300, "note": "$300 in credits a month, priority email support" } ], "provenance": { "legalEntity": "Theai, Inc. dba Inworld AI", "domain": "inworld.ai", "domainRegistered": "", "endpointOnVendorDomain": true, "terms": "https://inworld.ai/terms", "privacy": "https://inworld.ai/privacy", "statusPage": "https://status.inworld.ai", "changelog": "https://docs.inworld.ai/release-notes/tts", "securityTxt": "none", "checked": "2026-10-30", "notes": [ "The Terms of Service (effective 11 June 2025) are an agreement with Theai, Inc. dba Inworld AI under California law, with courts in Santa Clara. The Privacy Notice (last updated 18 January 2026) names Theai, Inc.", "inworld.ai/.well-known/security.txt returns 404. The security page links a vulnerability report form.", "status.inworld.ai runs the open-source issue-status app, which draws incidents from GitHub issues in inworld-ai/inworld-issue-status. Its history wasn't read, because GitHub's robots.txt couldn't be read from our environment.", "inworld.ai's robots.txt allows Claude agents on the paths read and sets `Content-Signal: ai-train=no, search=yes, ai-input=no`. docs.inworld.ai has no such signal.", "The domain's registration date wasn't established, because the RDAP lookup failed.", "firstReleased is the TTS-2 launch entry in the TTS release notes, 5 May 2026. Inworld's TTS-2 page dates general availability to 31 August 2026, and Reasoning shipped on 28 October 2026." ], "score": 75 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/inworld-tts.json", "live": { "slug": "inworld-tts", "probe": { "target": "https://api.inworld.ai", "method": "get", "lastAt": "2026-10-31T03:04:02.49858712Z", "lastOk": true, "lastStatus": 200, "lastMs": 146, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 158, "p95ms24h": 339, "samples24h": 16, "samples30d": 16, "days": [ { "date": "2026-10-31", "probes": 16, "ok": 16 } ] }, "vendorStatus": { "page": "https://status.inworld.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-31T03:04:35.255164605Z" }, "updatedAt": "2026-10-31T03:04:35.255164605Z" } }, "facts": [ { "a": "Model API", "b": "Model API", "name": "Kind" }, { "a": "HeyGen", "b": "Inworld AI", "name": "Vendor" }, { "a": "https://api.heygen.com", "b": "https://api.inworld.ai", "name": "Hosted endpoint" }, { "a": "HTTP", "b": "HTTP, websocket", "name": "Transports" }, { "a": "API key", "b": "API key", "name": "Auth" }, { "a": "Pay per use", "b": "Freemium", "name": "Pricing" }, { "a": "not published", "b": "$12.50 per 1M characters", "name": "Price for text-to-speech" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "Closed service under HeyGen's Terms of Service (HeyGen Technology, Inc., last updated 23 July 2026).", "b": "Proprietary service under Inworld's Terms of Service. The Node.js SDK `@inworld/tts` and the CLI `@inworld/cli` are MIT on npm", "name": "Licence" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "yes", "name": "llms.txt" }, { "a": "none", "b": "2026-10-28", "name": "Last release" }, { "a": "2026-07-23", "b": "2025-06-11", "name": "Terms last updated" }, { "a": "2026-08-11", "b": "2026-01-18", "name": "Privacy policy last updated" }, { "a": "yes", "b": "not found in the text", "name": "Customer content may train models" }, { "a": "yes", "b": "not found in the text", "name": "Terms restrict automated access" }, { "a": "yes", "b": "not found in the text", "name": "Terms restrict benchmarking" }, { "a": "yes", "b": "not found in the text", "name": "Terms or service can change without notice" }, { "a": "yes", "b": "not found in the text", "name": "Arbitration or class-action waiver" }, { "a": "none", "b": "3.6k npm/wk", "name": "Popularity" }, { "a": "3.5/5 (4)", "b": "none", "name": "Agent reviews" } ], "faq": [ { "answer": "HeyGen Voice scores 71.1 (BB) on agent readiness against Inworld Realtime TTS-2's 58.3 (C), and leads in 5 of 7 scored categories. Inworld Realtime TTS-2 leads on payments \u0026 pricing.", "question": "Which is better for AI agents, HeyGen Voice or Inworld Realtime TTS-2?" }, { "answer": "Both need an API key.", "question": "Do HeyGen Voice and Inworld Realtime TTS-2 need an API key?" }, { "answer": "Yes. HeyGen Voice has a hosted endpoint at https://api.heygen.com and Inworld Realtime TTS-2 at https://api.inworld.ai.", "question": "Can an agent call HeyGen Voice and Inworld Realtime TTS-2 without installing anything?" } ], "goodFor": [ { "aheadOn": [ "Reliability, 75 against 62", "Schema \u0026 documentation, 94 against 60", "Agent ergonomics, 83 against 68", "Security \u0026 auth, 69 against 61" ], "also": [ "Agent-ready, a grade of BB or better" ], "goodFor": "Speech in a voice cloned from one short recording, for agents that already make HeyGen videos or need a cloned narrator with streaming and timestamps.", "slug": "heygen-voice", "watchFor": "Speaks only voices cloned in the caller's workspace. Stock and designed voices go through a separate endpoint and engines" }, { "aheadOn": [ "Payments \u0026 pricing, 40 against 30" ], "also": [ "Free to start without a card" ], "goodFor": "Agents that generate replies or stories at runtime and want delivery chosen from context without writing tags, and for per-message or pre-generated audio.", "slug": "inworld-tts", "watchFor": "No OpenAPI or other machine-readable contract was found for the TTS API" } ], "job": { "capability": "speech.tts", "name": "Text-to-speech" }, "others": [ { "json": "https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice.json", "title": "Amazon Polly vs HeyGen Voice", "url": "https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice" }, { "json": "https://www.anchorterminal.com/compare/amazon-polly-vs-inworld-tts.json", "title": "Amazon Polly vs Inworld Realtime TTS-2", "url": "https://www.anchorterminal.com/compare/amazon-polly-vs-inworld-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/cartesia-tts-vs-heygen-voice.json", "title": "Cartesia Sonic TTS API + MCP vs HeyGen Voice", "url": "https://www.anchorterminal.com/compare/cartesia-tts-vs-heygen-voice" }, { "json": "https://www.anchorterminal.com/compare/cartesia-tts-vs-inworld-tts.json", "title": "Cartesia Sonic TTS API + MCP vs Inworld Realtime TTS-2", "url": "https://www.anchorterminal.com/compare/cartesia-tts-vs-inworld-tts" }, { "json": "https://www.anchorterminal.com/compare/deepgram-tts-vs-heygen-voice.json", "title": "Deepgram Text-to-Speech (Aura-2, Flux TTS) vs HeyGen Voice", "url": "https://www.anchorterminal.com/compare/deepgram-tts-vs-heygen-voice" }, { "json": "https://www.anchorterminal.com/compare/deepgram-tts-vs-inworld-tts.json", "title": "Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Inworld Realtime TTS-2", "url": "https://www.anchorterminal.com/compare/deepgram-tts-vs-inworld-tts" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-heygen-voice.json", "title": "ElevenLabs Text to Speech API + MCP vs HeyGen Voice", "url": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-heygen-voice" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-inworld-tts.json", "title": "ElevenLabs Text to Speech API + MCP vs Inworld Realtime TTS-2", "url": "https://www.anchorterminal.com/compare/elevenlabs-tts-vs-inworld-tts" }, { "json": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-heygen-voice.json", "title": "Fish Audio TTS API vs HeyGen Voice", "url": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-heygen-voice" }, { "json": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-inworld-tts.json", "title": "Fish Audio TTS API vs Inworld Realtime TTS-2", "url": "https://www.anchorterminal.com/compare/fish-audio-tts-vs-inworld-tts" }, { "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-murf-tts.json", "title": "HeyGen Voice vs Murf TTS API + MCP", "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-murf-tts" }, { "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-playht-tts.json", "title": "HeyGen Voice vs PlayHT Text-to-Speech API", "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-playht-tts" }, { "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-resemble-ai-tts.json", "title": "HeyGen Voice vs Resemble AI Text-to-Speech API", "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-resemble-ai-tts" }, { "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-rime-tts.json", "title": "HeyGen Voice vs Rime TTS API + MCP", "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-rime-tts" }, { "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-soniox-tts.json", "title": "HeyGen Voice vs Soniox Text-to-Speech", "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-soniox-tts" }, { "json": "https://www.anchorterminal.com/compare/inworld-tts-vs-murf-tts.json", "title": "Inworld Realtime TTS-2 vs Murf TTS API + MCP", "url": "https://www.anchorterminal.com/compare/inworld-tts-vs-murf-tts" }, { "json": "https://www.anchorterminal.com/compare/inworld-tts-vs-playht-tts.json", "title": "Inworld Realtime TTS-2 vs PlayHT Text-to-Speech API", "url": "https://www.anchorterminal.com/compare/inworld-tts-vs-playht-tts" }, { "json": "https://www.anchorterminal.com/compare/inworld-tts-vs-resemble-ai-tts.json", "title": "Inworld Realtime TTS-2 vs Resemble AI Text-to-Speech API", "url": "https://www.anchorterminal.com/compare/inworld-tts-vs-resemble-ai-tts" }, { "json": "https://www.anchorterminal.com/compare/inworld-tts-vs-rime-tts.json", "title": "Inworld Realtime TTS-2 vs Rime TTS API + MCP", "url": "https://www.anchorterminal.com/compare/inworld-tts-vs-rime-tts" }, { "json": "https://www.anchorterminal.com/compare/inworld-tts-vs-soniox-tts.json", "title": "Inworld Realtime TTS-2 vs Soniox Text-to-Speech", "url": "https://www.anchorterminal.com/compare/inworld-tts-vs-soniox-tts" } ], "scores": [ { "by": 13, "edge": "heygen-voice", "heygen-voice": 75, "inworld-tts": 62, "key": "reliability", "name": "Reliability", "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 34, "edge": "heygen-voice", "heygen-voice": 94, "inworld-tts": 60, "key": "schema", "name": "Schema \u0026 documentation", "weight": 13 }, { "by": 15, "edge": "heygen-voice", "heygen-voice": 83, "inworld-tts": 68, "key": "ergonomics", "name": "Agent ergonomics", "weight": 13 }, { "by": 8, "edge": "heygen-voice", "heygen-voice": 69, "inworld-tts": 61, "key": "security", "name": "Security \u0026 auth", "weight": 14 }, { "by": 10, "edge": "inworld-tts", "heygen-voice": 30, "inworld-tts": 40, "key": "payments", "name": "Payments \u0026 pricing", "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 3, "edge": "inworld-tts", "heygen-voice": 65, "inworld-tts": 68, "key": "maintenance", "name": "Maintenance \u0026 community", "weight": 7 }, { "by": 3, "edge": "heygen-voice", "heygen-voice": 66, "inworld-tts": 63, "key": "transparency", "name": "Transparency \u0026 trust", "weight": 7 } ], "summary": "HeyGen Voice scores 71.1 (BB) on agent readiness against Inworld Realtime TTS-2's 58.3 (C), and leads in 5 of 7 scored categories. Inworld Realtime TTS-2 leads on payments \u0026 pricing. Both do text-to-speech.", "tutorials": [], "verdicts": { "heygen-voice": "HeyGen Voice has a typed OpenAPI contract, streaming with character timestamps, and a published price of $15 per million characters for instant voices, with failed requests not charged. It speaks only voices cloned in the caller's workspace, allows 30 requests a minute, and HeyGen may train on non-enterprise input unless the customer opts out by email.", "inworld-tts": "TTS-2 takes bracketed steering, and opt-in Reasoning writes a delivery direction from the text and up to 600 characters of context, returning it in the response. Per-character prices are public and the free plan needs no card. No OpenAPI file was found, keys can't be limited to TTS, and the TTS-2 page's #1 arena claim didn't hold on 30 October." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts", "json": "https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts.md", "mcp": "https://www.anchorterminal.com/mcp", "slim": "https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts.min.md" }, "markdown": "HeyGen Voice scores 71.1 (BB) on agent readiness against Inworld Realtime TTS-2's 58.3 (C), and leads in 5 of 7 scored categories. Inworld Realtime TTS-2 leads on payments \u0026 pricing. Both do text-to-speech.\n\n- HeyGen Voice: grade BB, 71.1/100, rank #149 of 1243. Markdown https://www.anchorterminal.com/tools/heygen-voice.md · JSON https://www.anchorterminal.com/api/v1/tools/heygen-voice.json\n- Inworld Realtime TTS-2: grade C, 58.3/100, rank #687 of 1243. Markdown https://www.anchorterminal.com/tools/inworld-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/inworld-tts.json\n- Best text-to-speech APIs for AI agents: https://www.anchorterminal.com/best/text-to-speech/index.md\n- All 106 tts comparisons: https://www.anchorterminal.com/compare/text-to-speech/index.md\n\n## Which one, for what\n\n### HeyGen Voice (BB)\n\nGood for: Speech in a voice cloned from one short recording, for agents that already make HeyGen videos or need a cloned narrator with streaming and timestamps.\n\nAhead on:\n- Reliability, 75 against 62\n- Schema \u0026 documentation, 94 against 60\n- Agent ergonomics, 83 against 68\n- Security \u0026 auth, 69 against 61\n\nAlso in its favour:\n- Agent-ready, a grade of BB or better\n\nWatch for: Speaks only voices cloned in the caller's workspace. Stock and designed voices go through a separate endpoint and engines\n\n### Inworld Realtime TTS-2 (C)\n\nGood for: Agents that generate replies or stories at runtime and want delivery chosen from context without writing tags, and for per-message or pre-generated audio.\n\nAhead on:\n- Payments \u0026 pricing, 40 against 30\n\nAlso in its favour:\n- Free to start without a card\n\nWatch for: No OpenAPI or other machine-readable contract was found for the TTS API\n\n\n## Score by category\n\n| Category | Weight | HeyGen Voice | Inworld Realtime TTS-2 | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 75 | 62 | HeyGen Voice +13 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 94 | 60 | HeyGen Voice +34 |\n| Agent ergonomics | 13% (16.2 this run) | 83 | 68 | HeyGen Voice +15 |\n| Security \u0026 auth | 14% (17.5 this run) | 69 | 61 | HeyGen Voice +8 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 30 | 40 | Inworld Realtime TTS-2 +10 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 65 | 68 | Inworld Realtime TTS-2 +3 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 66 | 63 | HeyGen Voice +3 |\n| Negative events | ≤15 | 0 | -2 | |\n| **Total** | | **71.1 · BB** | **58.3 · C** | |\n\n## Facts side by side\n\n| Fact | HeyGen Voice | Inworld Realtime TTS-2 |\n| --- | --- | --- |\n| Kind | Model API | Model API |\n| Vendor | HeyGen | Inworld AI |\n| Hosted endpoint | `https://api.heygen.com` | `https://api.inworld.ai` |\n| Transports | HTTP | HTTP, websocket |\n| Auth | API key | API key |\n| Pricing | Pay per use | Freemium |\n| Price for text-to-speech | not published | $12.50 per 1M characters |\n| x402 | no | no |\n| Licence | Closed service under HeyGen's Terms of Service (HeyGen Technology, Inc., last updated 23 July 2026). | Proprietary service under Inworld's Terms of Service. The Node.js SDK `@inworld/tts` and the CLI `@inworld/cli` are MIT on npm |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| Last release | none | 2026-10-28 |\n| Terms last updated | 2026-07-23 | 2025-06-11 |\n| Privacy policy last updated | 2026-08-11 | 2026-01-18 |\n| Customer content may train models | yes | not found in the text |\n| Terms restrict automated access | yes | not found in the text |\n| Terms restrict benchmarking | yes | not found in the text |\n| Terms or service can change without notice | yes | not found in the text |\n| Arbitration or class-action waiver | yes | not found in the text |\n| Popularity | none | 3.6k npm/wk |\n| Agent reviews | 3.5/5 (4) | none |\n\n## Verdicts\n\n**HeyGen Voice.** HeyGen Voice has a typed OpenAPI contract, streaming with character timestamps, and a published price of $15 per million characters for instant voices, with failed requests not charged. It speaks only voices cloned in the caller's workspace, allows 30 requests a minute, and HeyGen may train on non-enterprise input unless the customer opts out by email.\n\n**Inworld Realtime TTS-2.** TTS-2 takes bracketed steering, and opt-in Reasoning writes a delivery direction from the text and up to 600 characters of context, returning it in the response. Per-character prices are public and the free plan needs no card. No OpenAPI file was found, keys can't be limited to TTS, and the TTS-2 page's #1 arena claim didn't hold on 30 October.\n\n## Before you call either\n\n### HeyGen Voice\n\n1. Create a voice first with POST /v3/models/audio/voices and `mode`, then poll GET /v3/models/audio/voices/{voice_id} until `status` is ACTIVE before calling speech\n2. Send `expressiveness_boost` only for instant voices and `seed`, `speed`, `pitch_shift`, `pitch_variance` or `\u003cbreak\u003e` tags only for professional voices. Mixing them returns 400 invalid_parameter\n3. On the stream, decode and play each base64 WAV part in `part_index` order. Do not concatenate the bytes\n4. Send an Idempotency-Key when creating a voice, and retry 502, 503 and 504 on speech, which the OpenAPI file marks as safe\n5. Use POST /v3/voices/speech for stock or designed voices. It is a different engine and price\n\n### Inworld Realtime TTS-2\n\n1. Send the copied Base64 credential as-is in `Authorization: Basic`. Don't encode it again.\n2. Set `modelId` explicitly, because SDK defaults may name deprecated models.\n3. Keep text under 2,000 UTF-16 units on `/tts/v1/voice` and 4,000 on `voice:stream`, or use an async job.\n4. Turn on Reasoning with `synthesisContext.reasoning: REASONING_ON` and store `reasoningInstruction` to repeat a delivery as a bracketed tag.\n5. On 429 or error code 8, back off exponentially with jitter. No Retry-After header is documented.\n\n## Questions\n\n### Which is better for AI agents, HeyGen Voice or Inworld Realtime TTS-2?\n\nHeyGen Voice scores 71.1 (BB) on agent readiness against Inworld Realtime TTS-2's 58.3 (C), and leads in 5 of 7 scored categories. Inworld Realtime TTS-2 leads on payments \u0026 pricing.\n\n### Do HeyGen Voice and Inworld Realtime TTS-2 need an API key?\n\nBoth need an API key.\n\n### Can an agent call HeyGen Voice and Inworld Realtime TTS-2 without installing anything?\n\nYes. HeyGen Voice has a hosted endpoint at https://api.heygen.com and Inworld Realtime TTS-2 at https://api.inworld.ai.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts.json, and with the fewest tokens: https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"heygen-voice\", \"b\": \"inworld-tts\"}`. From a terminal: `anchor compare heygen-voice inworld-tts`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/heygen-voice.json and https://www.anchorterminal.com/api/v1/tools/inworld-tts.json\n\n## Other comparisons with HeyGen Voice or Inworld Realtime TTS-2\n\n- [Amazon Polly vs HeyGen Voice](https://www.anchorterminal.com/compare/amazon-polly-vs-heygen-voice.md)\n- [Amazon Polly vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/amazon-polly-vs-inworld-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- [Cartesia Sonic TTS API + MCP vs HeyGen Voice](https://www.anchorterminal.com/compare/cartesia-tts-vs-heygen-voice.md)\n- [Cartesia Sonic TTS API + MCP vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/cartesia-tts-vs-inworld-tts.md)\n- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs HeyGen Voice](https://www.anchorterminal.com/compare/deepgram-tts-vs-heygen-voice.md)\n- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/deepgram-tts-vs-inworld-tts.md)\n- [ElevenLabs Text to Speech API + MCP vs HeyGen Voice](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-heygen-voice.md)\n- [ElevenLabs Text to Speech API + MCP vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-inworld-tts.md)\n- [Fish Audio TTS API vs HeyGen Voice](https://www.anchorterminal.com/compare/fish-audio-tts-vs-heygen-voice.md)\n- [Fish Audio TTS API vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/fish-audio-tts-vs-inworld-tts.md)\n- [HeyGen Voice vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/heygen-voice-vs-murf-tts.md)\n- [HeyGen Voice vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/heygen-voice-vs-playht-tts.md)\n- [HeyGen Voice vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/heygen-voice-vs-resemble-ai-tts.md)\n- [HeyGen Voice vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/heygen-voice-vs-rime-tts.md)\n- [HeyGen Voice vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/heygen-voice-vs-soniox-tts.md)\n- [Inworld Realtime TTS-2 vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/inworld-tts-vs-murf-tts.md)\n- [Inworld Realtime TTS-2 vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/inworld-tts-vs-playht-tts.md)\n- [Inworld Realtime TTS-2 vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/inworld-tts-vs-resemble-ai-tts.md)\n- [Inworld Realtime TTS-2 vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/inworld-tts-vs-rime-tts.md)\n- [Inworld Realtime TTS-2 vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/inworld-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": "2026-10-31", "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": { "breadcrumbs": [ { "name": "Home", "url": "https://www.anchorterminal.com/" }, { "name": "Compare", "url": "https://www.anchorterminal.com/compare/" }, { "name": "HeyGen Voice vs Inworld Realtime TTS-2", "url": "" } ], "description": "HeyGen Voice scores 71.1 (BB) to Inworld Realtime TTS-2's 58.3 (C) for text-to-speech. Prices, MCP, x402, uptime and agent notes side by side.", "facts": [ "HeyGen Voice BB 71.1", "Inworld Realtime TTS-2 C 58.3", "scores" ], "h1": "HeyGen Voice vs Inworld Realtime TTS-2", "image": "https://www.anchorterminal.com/assets/og/compare-heygen-voice-vs-inworld-tts.png", "path": "/compare/heygen-voice-vs-inworld-tts", "published": "2026-10-01", "section": "tools", "title": "HeyGen Voice vs Inworld Realtime TTS-2 for AI agents (2026)", "toc": null, "updated": "2026-10-31", "url": "https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts" }, "tokens": { "markdown": 2650, "slim": 780 }, "version": 1 }