{ "data": { "a": { "slug": "assemblyai-voice-agent", "name": "AssemblyAI Voice Agent API", "vendor": "AssemblyAI, Inc.", "vendorUrl": "https://www.assemblyai.com", "kind": "http-api", "category": "voice-agents", "summary": "AssemblyAI's Voice Agent API runs a spoken conversation over one WebSocket, combining its own speech-to-text, language model and text-to-speech. Agents are stored through a REST API and reached from a browser, a server or an inbound Twilio SIP number.", "url": "https://www.anchorterminal.com/tools/assemblyai-voice-agent", "markdownUrl": "https://www.anchorterminal.com/tools/assemblyai-voice-agent.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/assemblyai-voice-agent.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/assemblyai-voice-agent.json", "repo": "https://github.com/AssemblyAI/voice-agent-starter-python", "license": "Proprietary service under AssemblyAI's Terms of Service. The two starter repositories on GitHub carry no licence file", "transports": [ "http" ], "remoteUrl": "wss://agents.assemblyai.com/v1/ws", "packages": [], "auth": "api-key", "authNotes": "Self-serve API key from the dashboard, sent in the `Authorization` header on REST calls and on the WebSocket upgrade, with or without a `Bearer` prefix. Keys belong to a project and can be created and deleted in the dashboard (2 on the free plan, 4 on pay as you go, 25 on a contract). No scopes or expiry were found. Browser clients use a one-time token from `GET /v1/token`, redeemable within 1 to 600 seconds and passed as the `token` query parameter.", "pricing": "usage", "pricingNotes": "$4.50 an hour ($0.075 a minute), billed per second from socket open to session end, idle time included. The rate covers speech-to-text, the managed model, speech output, recordings and hosting. New accounts get $50 of credit with no card, which covers the Voice Agent API. LLM Gateway tokens and Twilio carrier minutes are billed separately. Volume pricing is by sales contact (https://www.assemblyai.com/pricing, https://www.assemblyai.com/docs/billing-and-pricing, checked 2026-10-09).", "priceSummary": "Pay per use", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the Voice Agent docs, the two API description files, the billing docs or the pricing page. Payment is by card into a prepaid balance (checked 2026-10-09).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": null, "npmWeekly": null, "pypiWeekly": null, "asOf": "2026-10-09" }, "docsUrl": "https://www.assemblyai.com/docs/voice-agents/voice-agent-api", "llmsTxt": "https://www.assemblyai.com/docs/llms.txt", "openapi": "https://www.assemblyai.com/docs/api-reference/specs/voice-agent-api.yaml", "capabilities": [ "voice.agent", "voice.pipeline", "voice.tools", "voice.telephony" ], "tags": [ "hosted", "no-card", "closed-source", "llms-txt", "webhooks", "streaming", "pipeline", "python", "javascript", "status-page", "soc2" ], "lastRelease": "2026-08-26", "graded": true, "anchor": { "graded": true, "score": 64.4, "grade": "B", "agentReady": false, "rank": 351, "ranked": true, "rankOf": 950, "categoryRank": 4, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 72, "maintenance": 64, "payments": 40, "reliability": 60, "schema": 83, "security": 62, "transparency": 66 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-09" }, "negative": 0, "verdict": "One $0.075 a minute rate covers speech-to-text, the managed model, speech output, recordings and hosting, and the socket has an AsyncAPI file, typed error codes and a 30-second resume window. No concurrent-session limit is published, the status page has no Voice Agent component, and phone calls are inbound only through a Twilio trunk the customer owns.", "bestFor": "A developer who wants one managed pipeline at a flat rate and is content with AssemblyAI's own speech models and voices, with an optional model of their own.", "strengths": [ "One published rate of $4.50 an hour ($0.075 a minute), billed per second, with $50 of credit and no card for new accounts", "AsyncAPI 3.0 file for the socket, an OpenAPI file for the token endpoint, llms.txt and a Markdown copy of every docs page", "Session errors carry a code, a message and sometimes the offending field, and the docs name the three codes that are safe to retry", "HTTP tool header values are write-only and encrypted at rest, and tool calls are limited to public `https` hosts with redirects refused", "Every session is stored with a stereo recording, a JSON timeline of turns and tool calls, and signed webhooks with a delivery history" ], "weaknesses": [ "No number is published for the concurrent-session limit that the `concurrency_exceeded` error enforces", "status.assemblyai.com lists the Asynchronous API, Streaming API and LLM Gateway, with no Voice Agent component", "Telephony is inbound only, over a SIP trunk on a Twilio account the customer owns", "API keys have no scopes or expiry, and opting out of model training needs a paid plan", "The Terms of Service bar benchmarking and competitive analysis (2.4(f)) and any automated or programmatic method of extracting data or Output (4.4), which matters before any probe is run" ], "agentNotes": [ "Send `session.end` before closing the socket. Without it the session stays resumable, and billed, for 30 seconds", "Retry only `at_capacity`, `concurrency_exceeded` and `internal_error`, with backoff. Every other session error code is fatal", "Send `tool.result` inside the `reply.done` handler, not straight after `tool.call`", "Mint a one-time token with `GET /v1/token` for browser clients and never ship the API key to a page", "Deduplicate webhooks on `event_id`, and verify `X-AAI-Signature` against the raw body bytes because a 401 is not retried" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "B", "methodology": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 64.4 } ], "editorialScores": { "ergonomics": 72, "maintenance": 64, "payments": 40, "reliability": 60, "schema": 83, "security": 62, "transparency": 51 }, "provenanceScore": 81 }, "connect": { "install": "git clone https://github.com/AssemblyAI/voice-agent-starter-python", "http": "curl -X POST https://agents.assemblyai.com/v1/agents \\\n -H \"Authorization: $ASSEMBLYAI_API_KEY\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\"name\": \"Support Assistant\", \"system_prompt\": \"You are a friendly support agent.\", \"greeting\": \"Hi, how can I help?\", \"voice\": {\"voice_id\": \"alba\"}}'", "claudeCode": "claude mcp add --transport http --scope user assemblyai-docs https://mcp.assemblyai.com/docs" }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/assemblyai-voice-agent" }, "sameCompany": [ "assemblyai-stt" ], "area": "voice", "unitPrices": [ { "item": "Voice Agent session", "unit": "call-minute", "usd": 0.075, "note": "$4.50 an hour billed per second of open socket. Speech-to-text, managed model, speech output and recordings included. LLM Gateway tokens and carrier minutes extra" } ], "provenance": { "legalEntity": "AssemblyAI, Inc.", "domain": "assemblyai.com", "domainRegistered": "2016-12-24", "endpointOnVendorDomain": true, "terms": "https://www.assemblyai.com/legal/terms-of-service", "privacy": "https://www.assemblyai.com/legal/privacy-policy", "statusPage": "https://status.assemblyai.com", "changelog": "https://www.assemblyai.com/changelog", "securityTxt": "unknown", "checked": "2026-10-09", "score": 81 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/assemblyai-voice-agent.json", "live": { "slug": "assemblyai-voice-agent", "probe": { "target": "wss://agents.assemblyai.com/v1/ws", "method": "get", "lastAt": "2026-10-10T03:53:19.457306073Z", "lastOk": false, "lastStatus": 0, "lastMs": 0, "lastNote": "unsupported protocol scheme \"wss\"", "authRequired": false, "uptime24h": 0, "uptime30d": 0, "p50ms24h": 0, "p95ms24h": 0, "samples24h": 125, "samples30d": 125, "days": [ { "date": "2026-10-09", "probes": 85, "ok": 0 }, { "date": "2026-10-10", "probes": 40, "ok": 0 } ], "outages": [ { "start": "2026-10-09T15:42:56.660671906Z", "end": "0001-01-01T00:00:00Z", "note": "unsupported protocol scheme \"wss\"" } ] }, "vendorStatus": { "page": "https://status.assemblyai.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-10T03:57:59.907485515Z" }, "githubStars": 3, "pages": [ { "url": "https://www.assemblyai.com/docs/billing-and-pricing", "kind": "pricing", "status": 200, "checkedAt": "2026-10-09T18:48:16.435584974Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "3b80ad9644cf" } ], "updatedAt": "2026-10-10T03:57:59.907485515Z" } }, "answer": "AssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against Bolna API + MCP's 52.6 (D), and leads in 5 of 7 scored categories. Bolna API + MCP leads on maintenance \u0026 community.", "b": { "slug": "bolna", "name": "Bolna API + MCP", "vendor": "Bolna", "vendorUrl": "https://www.bolna.ai", "kind": "http-api", "category": "voice-agents", "summary": "Voice-agent platform built for Indian languages and phone campaigns.", "url": "https://www.anchorterminal.com/tools/bolna", "markdownUrl": "https://www.anchorterminal.com/tools/bolna.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/bolna.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/bolna.json", "repo": "https://github.com/bolna-ai/bolna", "license": "MIT", "transports": [ "http", "streamable-http" ], "remoteUrl": "https://api.bolna.ai", "packages": [ { "registry": "pypi", "name": "bolna" }, { "registry": "npm", "name": "@bolna/web-call" } ], "auth": "api-key", "authNotes": "Bearer API key (`bn-...`, or `sa-...` for a sub-account) from the dashboard, shown once and stored hashed. The hosted MCP at `https://mcp.bolna.ai/api/mcp` takes the same key as a Bearer header, and every MCP tool accepts an `api_key` argument to act as a sub-account. The Web Call SDK mints single-use browser sessions that expire in about 120 seconds, so the key stays server-side. Webhooks and tool calls carry no signature. Bolna says to allowlist its 3 source IPs instead.", "pricing": "usage", "pricingNotes": "Prepaid wallet from $10 to $5,000 with $5 free credit at signup. Standard rate $0.06 a minute (₹5.52) covers Voice AI on the preferred STT, LLM and TTS models, falling to about $0.045 on larger top-ups. Telephony and a Bolna platform fee are billed on top, and non-preferred models are billed per use. Pilot plans are one-off, $300 for 6,500 minutes or $500 for 12,000 minutes, billed in 30-second pulses with 25 concurrent calls. Bringing your own STT, LLM and TTS keys leaves only the platform fee and telephony. Enterprise is custom (https://www.bolna.ai/pricing).", "priceSummary": "Pay per use", "where": "hosted", "x402": { "level": "no", "evidence": "No x402 support in the docs, pricing page or MCP docs (checked 2026-09-30).", "endpoints": [] }, "toolCount": 84, "popularity": { "githubStars": 779, "npmWeekly": 579, "pypiWeekly": 2601, "asOf": "2026-09-30" }, "docsUrl": "https://www.bolna.ai/docs", "llmsTxt": "https://www.bolna.ai/docs/llms.txt", "capabilities": [ "voice.agent", "voice.pipeline", "voice.speech-to-speech", "voice.tools", "voice.telephony" ], "tags": [ "hosted", "open-source", "self-hosted", "mcp", "llms-txt", "python", "typescript", "webhooks", "pipeline", "speech-to-speech", "enterprise" ], "lastRelease": "2026-09-29", "graded": true, "anchor": { "graded": true, "score": 52.6, "grade": "D", "agentReady": false, "rank": 729, "ranked": true, "rankOf": 950, "categoryRank": 12, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 52, "maintenance": 76, "payments": 30, "reliability": 50, "schema": 63, "security": 44, "transparency": 66 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": 0, "verdict": "Transcriber, LLM and voice chosen per agent, or one OpenAI Realtime or Gemini Live model. Unsigned webhooks and tool calls, IP allowlisting only.", "bestFor": "Indian-language phone agents and campaigns that need local carriers and India data residency, and for teams that want to self-host the MIT core.", "strengths": [ "Transcriber, LLM and voice chosen per agent, or one OpenAI Realtime or Gemini Live model", "Indian telephony through Plivo, Exotel and Vobiz, with an India data-residency option in ap-south-1", "Hosted MCP server with 84 tools, 23 of them carrying `destructiveHint`", "MIT-licensed core framework, released to PyPI almost daily", "Published per-endpoint rate limits with 429 and backoff guidance" ], "weaknesses": [ "Unsigned webhooks and tool calls, IP allowlisting only", "No security.txt, bug bounty or SOC 2 claim found", "The OpenAPI link in llms.txt returns 404", "Telephony and platform fees aren't priced on the pricing page", "Terms and privacy policy name different legal entities" ], "agentNotes": [ "Wait for the `completed` execution status, not `call-disconnected`, before reading cost, recording or extracted data", "Send `scheduled_at` with a numeric offset such as `+00:00`, since a `Z` suffix returns 500", "Back off exponentially on 429, the limit on `/call` is 500 requests a minute", "Reject webhook and tool requests that don't come from 13.203.39.153, 13.126.9.249 or 13.202.133.53", "Leave the MCP `api_key` argument empty unless acting as a sub-account, so the key stays out of the transcript" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 2.5, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "D", "methodology": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 52.6 } ], "editorialScores": { "ergonomics": 52, "maintenance": 76, "payments": 30, "reliability": 50, "schema": 63, "security": 44, "transparency": 57 }, "provenanceScore": 75 }, "connect": { "http": "curl -X POST https://api.bolna.ai/call -H \"Authorization: Bearer $BOLNA_API_KEY\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\"agent_id\":\"123e4567-e89b-12d3-a456-426655440000\",\"recipient_phone_number\":\"+919876543210\"}'", "claudeCode": "claude mcp add --transport http bolna https://mcp.bolna.ai/api/mcp --header \"Authorization: Bearer $BOLNA_API_KEY\"", "config": { "mcpServers": { "bolna": { "args": [ "-y", "mcp-remote", "https://mcp.bolna.ai/api/mcp", "--header", "Authorization: Bearer ${BOLNA_API_KEY}" ], "command": "npx" } } } }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/bolna" }, "area": "voice", "unitPrices": [ { "item": "Standard rate, preferred models", "unit": "call-minute", "usd": 0.06, "note": "Voice AI only, telephony and platform fee extra" }, { "item": "Pilot plan, 12,000 minutes", "unit": "call-minute", "usd": 0.042, "note": "one-off $500, 25 concurrent calls" }, { "item": "Pilot plan, 6,500 minutes", "unit": "call-minute", "usd": 0.046, "note": "one-off $300" } ], "provenance": { "legalEntity": "Voxlabs Private Limited", "domain": "bolna.ai", "domainRegistered": "2024-09-27", "domainNote": "The registry date is later than Bolna's first PyPI release (2024-01-01), so the domain was probably re-registered. Support mail also uses bolna.dev.", "endpointOnVendorDomain": true, "terms": "https://www.bolna.ai/terms-of-service", "privacy": "https://www.bolna.ai/privacy-policy", "statusPage": "https://status.bolna.ai", "changelog": "https://www.bolna.ai/docs/changelog", "securityTxt": "none", "checked": "2026-10-01", "notes": [ "The terms name Voxlabs Private Limited, operating as Bolna. The privacy policy (updated 2025-03-28) and the site footer name Whismurwave Inc." ], "score": 75 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/bolna.json", "live": { "slug": "bolna", "probe": { "target": "https://api.bolna.ai", "method": "get", "lastAt": "2026-10-10T03:53:21.888185915Z", "lastOk": true, "lastStatus": 404, "lastMs": 734, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 743, "p95ms24h": 824, "samples24h": 249, "samples30d": 2476, "days": [ { "date": "2026-09-30", "probes": 35, "ok": 35 }, { "date": "2026-10-01", "probes": 276, "ok": 276 }, { "date": "2026-10-02", "probes": 248, "ok": 248 }, { "date": "2026-10-03", "probes": 271, "ok": 271 }, { "date": "2026-10-04", "probes": 272, "ok": 272 }, { "date": "2026-10-05", "probes": 272, "ok": 272 }, { "date": "2026-10-06", "probes": 272, "ok": 272 }, { "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": 40, "ok": 40 } ] }, "vendorStatus": { "page": "https://status.bolna.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-10T00:50:10.891172194Z" }, "versions": [ { "registry": "github", "name": "bolna-ai/bolna", "version": "0.10.283", "released": "2026-10-09", "seenAt": "2026-10-09T16:43:18.541801038Z" }, { "registry": "npm", "name": "@bolna/web-call", "version": "3.0.1", "seenAt": "2026-10-09T16:43:17.678084684Z" }, { "registry": "pypi", "name": "bolna", "version": "0.10.283", "released": "2026-10-09", "seenAt": "2026-10-09T16:43:17.561357553Z" } ], "githubStars": 787, "npmWeekly": 355, "pypiWeekly": 3127, "securityTxt": { "url": "https://bolna.ai/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-09T15:40:15.610136945Z" }, "llmsTxt": { "url": "https://www.bolna.ai/docs/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-09T14:01:33.380529628Z" }, "domain": { "domain": "bolna.ai", "registered": "2024-09-27", "source": "https://rdap.identitydigital.services/rdap/domain/bolna.ai", "checkedAt": "2026-10-04T13:07:18.917906737Z" }, "pages": [ { "url": "https://www.bolna.ai/docs/changelog", "kind": "changelog", "status": 200, "checkedAt": "2026-10-09T18:48:37.654724324Z", "changedAt": "2026-10-08T18:26:37.791224417Z", "fingerprint": "e86241a07812" }, { "url": "https://www.bolna.ai/pricing", "kind": "pricing", "status": 200, "checkedAt": "2026-10-09T18:48:40.422639241Z", "changedAt": "2026-10-08T18:26:40.317117734Z", "fingerprint": "fa31e090be77" }, { "url": "https://www.bolna.ai/privacy-policy", "kind": "privacy", "status": 200, "checkedAt": "2026-10-09T18:48:41.717327011Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "0f8133e9e865" }, { "url": "https://www.bolna.ai/terms-of-service", "kind": "terms", "status": 200, "checkedAt": "2026-10-09T18:48:43.804112028Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "561e3b6c9a44" } ], "updatedAt": "2026-10-10T03:53:21.888185915Z" } }, "facts": [ { "a": "HTTP API", "b": "HTTP API", "name": "Kind" }, { "a": "AssemblyAI, Inc.", "b": "Bolna", "name": "Vendor" }, { "a": "wss://agents.assemblyai.com/v1/ws", "b": "https://api.bolna.ai", "name": "Hosted endpoint" }, { "a": "HTTP", "b": "HTTP, Streamable HTTP", "name": "Transports" }, { "a": "API key", "b": "API key", "name": "Auth" }, { "a": "Pay per use", "b": "Pay per use", "name": "Pricing" }, { "a": "$0.075 per minute of call", "b": "not published", "name": "Price for voice agents" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "Proprietary service under AssemblyAI's Terms of Service. The two starter repositories on GitHub carry no licence file", "b": "MIT", "name": "Licence" }, { "a": "none", "b": "84", "name": "Tools exposed" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "yes", "name": "llms.txt" }, { "a": "2026-08-26", "b": "2026-09-29", "name": "Last release" }, { "a": "2026-07-01", "b": "2026-08-13", "name": "Terms last updated" }, { "a": "2026-05-26", "b": "2025-03-28", "name": "Privacy policy last updated" }, { "a": "yes, with an opt-out", "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": "yes", "name": "Terms restrict benchmarking" }, { "a": "not found in the text", "b": "yes", "name": "Terms or service can change without notice" }, { "a": "not found in the text", "b": "not found in the text", "name": "Arbitration or class-action waiver" }, { "a": "none", "b": "779 stars, 579 npm/wk, 2.6k PyPI/wk", "name": "Popularity" }, { "a": "none", "b": "2.5/5 (2)", "name": "Agent reviews" } ], "faq": [ { "answer": "AssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against Bolna API + MCP's 52.6 (D), and leads in 5 of 7 scored categories. Bolna API + MCP leads on maintenance \u0026 community.", "question": "Which is better for AI agents, AssemblyAI Voice Agent API or Bolna API + MCP?" }, { "answer": "Both need an API key.", "question": "Do AssemblyAI Voice Agent API and Bolna API + MCP need an API key?" }, { "answer": "Yes. AssemblyAI Voice Agent API has a hosted endpoint at wss://agents.assemblyai.com/v1/ws and Bolna API + MCP at https://api.bolna.ai.", "question": "Can an agent call AssemblyAI Voice Agent API and Bolna API + MCP without installing anything?" }, { "answer": "No open-source release is listed for AssemblyAI Voice Agent API. Bolna API + MCP is open source (MIT).", "question": "Are AssemblyAI Voice Agent API and Bolna API + MCP open source?" } ], "goodFor": [ { "aheadOn": [ "Reliability, 60 against 50", "Schema \u0026 documentation, 83 against 63", "Agent ergonomics, 72 against 52", "Security \u0026 auth, 62 against 44", "Payments \u0026 pricing, 40 against 30" ], "also": [ "Free to start without a card" ], "goodFor": "A developer who wants one managed pipeline at a flat rate and is content with AssemblyAI's own speech models and voices, with an optional model of their own.", "slug": "assemblyai-voice-agent", "watchFor": "No number is published for the concurrent-session limit that the `concurrency_exceeded` error enforces" }, { "aheadOn": [ "Maintenance \u0026 community, 76 against 64" ], "also": [ "Open source" ], "goodFor": "Indian-language phone agents and campaigns that need local carriers and India data residency, and for teams that want to self-host the MIT core.", "slug": "bolna", "watchFor": "Unsigned webhooks and tool calls, IP allowlisting only" } ], "job": { "capability": "voice.agent", "name": "Voice agents" }, "others": [ { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-ai.json", "title": "AssemblyAI Voice Agent API vs Bland AI API + MCP", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-ai" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-deepgram-voice-agent.json", "title": "AssemblyAI Voice Agent API vs Deepgram Voice Agent API", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-deepgram-voice-agent" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-elevenlabs-agents.json", "title": "AssemblyAI Voice Agent API vs ElevenLabs Agents API + MCP", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-elevenlabs-agents" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gemini-live.json", "title": "AssemblyAI Voice Agent API vs Gemini Live API", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gemini-live" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-hume-evi.json", "title": "AssemblyAI Voice Agent API vs Hume EVI (Empathic Voice Interface)", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-hume-evi" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-openai-realtime.json", "title": "AssemblyAI Voice Agent API vs OpenAI Realtime API", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-openai-realtime" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-retell-ai.json", "title": "AssemblyAI Voice Agent API vs Retell AI API + MCP", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-retell-ai" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-synthflow.json", "title": "AssemblyAI Voice Agent API vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-synthflow" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox.json", "title": "AssemblyAI Voice Agent API vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vapi.json", "title": "AssemblyAI Voice Agent API vs Vapi API + MCP", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vapi" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vocily.json", "title": "AssemblyAI Voice Agent API vs Vocily AI", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vocily" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vogent.json", "title": "AssemblyAI Voice Agent API vs Vogent API", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vogent" }, { "json": "https://www.anchorterminal.com/compare/bland-ai-vs-bolna.json", "title": "Bland AI API + MCP vs Bolna API + MCP", "url": "https://www.anchorterminal.com/compare/bland-ai-vs-bolna" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-deepgram-voice-agent.json", "title": "Bolna API + MCP vs Deepgram Voice Agent API", "url": "https://www.anchorterminal.com/compare/bolna-vs-deepgram-voice-agent" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-elevenlabs-agents.json", "title": "Bolna API + MCP vs ElevenLabs Agents API + MCP", "url": "https://www.anchorterminal.com/compare/bolna-vs-elevenlabs-agents" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-gemini-live.json", "title": "Bolna API + MCP vs Gemini Live API", "url": "https://www.anchorterminal.com/compare/bolna-vs-gemini-live" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-hume-evi.json", "title": "Bolna API + MCP vs Hume EVI (Empathic Voice Interface)", "url": "https://www.anchorterminal.com/compare/bolna-vs-hume-evi" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-openai-realtime.json", "title": "Bolna API + MCP vs OpenAI Realtime API", "url": "https://www.anchorterminal.com/compare/bolna-vs-openai-realtime" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-retell-ai.json", "title": "Bolna API + MCP vs Retell AI API + MCP", "url": "https://www.anchorterminal.com/compare/bolna-vs-retell-ai" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-synthflow.json", "title": "Bolna API + MCP vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/bolna-vs-synthflow" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-ultravox.json", "title": "Bolna API + MCP vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/bolna-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-vapi.json", "title": "Bolna API + MCP vs Vapi API + MCP", "url": "https://www.anchorterminal.com/compare/bolna-vs-vapi" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-vocily.json", "title": "Bolna API + MCP vs Vocily AI", "url": "https://www.anchorterminal.com/compare/bolna-vs-vocily" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-vogent.json", "title": "Bolna API + MCP vs Vogent API", "url": "https://www.anchorterminal.com/compare/bolna-vs-vogent" } ], "scores": [ { "assemblyai-voice-agent": 60, "bolna": 50, "by": 10, "edge": "assemblyai-voice-agent", "key": "reliability", "name": "Reliability", "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "assemblyai-voice-agent": 83, "bolna": 63, "by": 20, "edge": "assemblyai-voice-agent", "key": "schema", "name": "Schema \u0026 documentation", "weight": 13 }, { "assemblyai-voice-agent": 72, "bolna": 52, "by": 20, "edge": "assemblyai-voice-agent", "key": "ergonomics", "name": "Agent ergonomics", "weight": 13 }, { "assemblyai-voice-agent": 62, "bolna": 44, "by": 18, "edge": "assemblyai-voice-agent", "key": "security", "name": "Security \u0026 auth", "weight": 14 }, { "assemblyai-voice-agent": 40, "bolna": 30, "by": 10, "edge": "assemblyai-voice-agent", "key": "payments", "name": "Payments \u0026 pricing", "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "assemblyai-voice-agent": 64, "bolna": 76, "by": 12, "edge": "bolna", "key": "maintenance", "name": "Maintenance \u0026 community", "weight": 7 }, { "assemblyai-voice-agent": 66, "bolna": 66, "by": 0, "edge": "", "key": "transparency", "name": "Transparency \u0026 trust", "weight": 7 } ], "summary": "AssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against Bolna API + MCP's 52.6 (D), and leads in 5 of 7 scored categories. Bolna API + MCP leads on maintenance \u0026 community. Both do voice agents.", "verdicts": { "assemblyai-voice-agent": "One $0.075 a minute rate covers speech-to-text, the managed model, speech output, recordings and hosting, and the socket has an AsyncAPI file, typed error codes and a 30-second resume window. No concurrent-session limit is published, the status page has no Voice Agent component, and phone calls are inbound only through a Twilio trunk the customer owns.", "bolna": "Transcriber, LLM and voice chosen per agent, or one OpenAI Realtime or Gemini Live model. Unsigned webhooks and tool calls, IP allowlisting only." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bolna", "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bolna.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bolna.md", "slim": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bolna.min.md" }, "markdown": "AssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against Bolna API + MCP's 52.6 (D), and leads in 5 of 7 scored categories. Bolna API + MCP leads on maintenance \u0026 community. Both do voice agents.\n\n- AssemblyAI Voice Agent API: grade B, 64.4/100, rank #351 of 950. Markdown https://www.anchorterminal.com/tools/assemblyai-voice-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/assemblyai-voice-agent.json\n- Bolna API + MCP: grade D, 52.6/100, rank #729 of 950. Markdown https://www.anchorterminal.com/tools/bolna.md · JSON https://www.anchorterminal.com/api/v1/tools/bolna.json\n- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md\n- All 91 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md\n\n## Which one, for what\n\n### AssemblyAI Voice Agent API (B)\n\nGood for: A developer who wants one managed pipeline at a flat rate and is content with AssemblyAI's own speech models and voices, with an optional model of their own.\n\nAhead on:\n- Reliability, 60 against 50\n- Schema \u0026 documentation, 83 against 63\n- Agent ergonomics, 72 against 52\n- Security \u0026 auth, 62 against 44\n- Payments \u0026 pricing, 40 against 30\n\nAlso in its favour:\n- Free to start without a card\n\nWatch for: No number is published for the concurrent-session limit that the `concurrency_exceeded` error enforces\n\n### Bolna API + MCP (D)\n\nGood for: Indian-language phone agents and campaigns that need local carriers and India data residency, and for teams that want to self-host the MIT core.\n\nAhead on:\n- Maintenance \u0026 community, 76 against 64\n\nAlso in its favour:\n- Open source\n\nWatch for: Unsigned webhooks and tool calls, IP allowlisting only\n\n\n## Score by category\n\n| Category | Weight | AssemblyAI Voice Agent API | Bolna API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 60 | 50 | AssemblyAI Voice Agent API +10 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 83 | 63 | AssemblyAI Voice Agent API +20 |\n| Agent ergonomics | 13% (16.2 this run) | 72 | 52 | AssemblyAI Voice Agent API +20 |\n| Security \u0026 auth | 14% (17.5 this run) | 62 | 44 | AssemblyAI Voice Agent API +18 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 40 | 30 | AssemblyAI Voice Agent API +10 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 64 | 76 | Bolna API + MCP +12 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 66 | 66 | even |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **64.4 · B** | **52.6 · D** | |\n\n## Facts side by side\n\n| Fact | AssemblyAI Voice Agent API | Bolna API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | AssemblyAI, Inc. | Bolna |\n| Hosted endpoint | `wss://agents.assemblyai.com/v1/ws` | `https://api.bolna.ai` |\n| Transports | HTTP | HTTP, Streamable HTTP |\n| Auth | API key | API key |\n| Pricing | Pay per use | Pay per use |\n| Price for voice agents | $0.075 per minute of call | not published |\n| x402 | no | no |\n| Licence | Proprietary service under AssemblyAI's Terms of Service. The two starter repositories on GitHub carry no licence file | MIT |\n| Tools exposed | none | 84 |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| Last release | 2026-08-26 | 2026-09-29 |\n| Terms last updated | 2026-07-01 | 2026-08-13 |\n| Privacy policy last updated | 2026-05-26 | 2025-03-28 |\n| Customer content may train models | yes, with an opt-out | not found in the text |\n| Terms restrict automated access | yes | not found in the text |\n| Terms restrict benchmarking | yes | yes |\n| Terms or service can change without notice | not found in the text | yes |\n| Arbitration or class-action waiver | not found in the text | not found in the text |\n| Popularity | none | 779 stars, 579 npm/wk, 2.6k PyPI/wk |\n| Agent reviews | none | 2.5/5 (2) |\n\n## Verdicts\n\n**AssemblyAI Voice Agent API.** One $0.075 a minute rate covers speech-to-text, the managed model, speech output, recordings and hosting, and the socket has an AsyncAPI file, typed error codes and a 30-second resume window. No concurrent-session limit is published, the status page has no Voice Agent component, and phone calls are inbound only through a Twilio trunk the customer owns.\n\n**Bolna API + MCP.** Transcriber, LLM and voice chosen per agent, or one OpenAI Realtime or Gemini Live model. Unsigned webhooks and tool calls, IP allowlisting only.\n\n## Before you call either\n\n### AssemblyAI Voice Agent API\n\n1. Send `session.end` before closing the socket. Without it the session stays resumable, and billed, for 30 seconds\n2. Retry only `at_capacity`, `concurrency_exceeded` and `internal_error`, with backoff. Every other session error code is fatal\n3. Send `tool.result` inside the `reply.done` handler, not straight after `tool.call`\n4. Mint a one-time token with `GET /v1/token` for browser clients and never ship the API key to a page\n5. Deduplicate webhooks on `event_id`, and verify `X-AAI-Signature` against the raw body bytes because a 401 is not retried\n\n### Bolna API + MCP\n\n1. Wait for the `completed` execution status, not `call-disconnected`, before reading cost, recording or extracted data\n2. Send `scheduled_at` with a numeric offset such as `+00:00`, since a `Z` suffix returns 500\n3. Back off exponentially on 429, the limit on `/call` is 500 requests a minute\n4. Reject webhook and tool requests that don't come from 13.203.39.153, 13.126.9.249 or 13.202.133.53\n5. Leave the MCP `api_key` argument empty unless acting as a sub-account, so the key stays out of the transcript\n\n## Questions\n\n### Which is better for AI agents, AssemblyAI Voice Agent API or Bolna API + MCP?\n\nAssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against Bolna API + MCP's 52.6 (D), and leads in 5 of 7 scored categories. Bolna API + MCP leads on maintenance \u0026 community.\n\n### Do AssemblyAI Voice Agent API and Bolna API + MCP need an API key?\n\nBoth need an API key.\n\n### Can an agent call AssemblyAI Voice Agent API and Bolna API + MCP without installing anything?\n\nYes. AssemblyAI Voice Agent API has a hosted endpoint at wss://agents.assemblyai.com/v1/ws and Bolna API + MCP at https://api.bolna.ai.\n\n### Are AssemblyAI Voice Agent API and Bolna API + MCP open source?\n\nNo open-source release is listed for AssemblyAI Voice Agent API. Bolna API + MCP is open source (MIT).\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bolna.json, and with the fewest tokens: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bolna.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"assemblyai-voice-agent\", \"b\": \"bolna\"}`. From a terminal: `anchor compare assemblyai-voice-agent bolna`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/assemblyai-voice-agent.json and https://www.anchorterminal.com/api/v1/tools/bolna.json\n\n## Other comparisons with AssemblyAI Voice Agent API or Bolna API + MCP\n\n- [AssemblyAI Voice Agent API vs Bland AI API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-ai.md)\n- [AssemblyAI Voice Agent API vs Deepgram Voice Agent API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-deepgram-voice-agent.md)\n- [AssemblyAI Voice Agent API vs ElevenLabs Agents API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-elevenlabs-agents.md)\n- [AssemblyAI Voice Agent API vs Gemini Live API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gemini-live.md)\n- [AssemblyAI Voice Agent API vs Hume EVI (Empathic Voice Interface)](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-hume-evi.md)\n- [AssemblyAI Voice Agent API vs OpenAI Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-openai-realtime.md)\n- [AssemblyAI Voice Agent API vs Retell AI API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-retell-ai.md)\n- [AssemblyAI Voice Agent API vs Synthflow API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-synthflow.md)\n- [AssemblyAI Voice Agent API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox.md)\n- [AssemblyAI Voice Agent API vs Vapi API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vapi.md)\n- [AssemblyAI Voice Agent API vs Vocily AI](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vocily.md)\n- [AssemblyAI Voice Agent API vs Vogent API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vogent.md)\n- [Bland AI API + MCP vs Bolna API + MCP](https://www.anchorterminal.com/compare/bland-ai-vs-bolna.md)\n- [Bolna API + MCP vs Deepgram Voice Agent API](https://www.anchorterminal.com/compare/bolna-vs-deepgram-voice-agent.md)\n- [Bolna API + MCP vs ElevenLabs Agents API + MCP](https://www.anchorterminal.com/compare/bolna-vs-elevenlabs-agents.md)\n- [Bolna API + MCP vs Gemini Live API](https://www.anchorterminal.com/compare/bolna-vs-gemini-live.md)\n- [Bolna API + MCP vs Hume EVI (Empathic Voice Interface)](https://www.anchorterminal.com/compare/bolna-vs-hume-evi.md)\n- [Bolna API + MCP vs OpenAI Realtime API](https://www.anchorterminal.com/compare/bolna-vs-openai-realtime.md)\n- [Bolna API + MCP vs Retell AI API + MCP](https://www.anchorterminal.com/compare/bolna-vs-retell-ai.md)\n- [Bolna API + MCP vs Synthflow API + MCP](https://www.anchorterminal.com/compare/bolna-vs-synthflow.md)\n- [Bolna API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/bolna-vs-ultravox.md)\n- [Bolna API + MCP vs Vapi API + MCP](https://www.anchorterminal.com/compare/bolna-vs-vapi.md)\n- [Bolna API + MCP vs Vocily AI](https://www.anchorterminal.com/compare/bolna-vs-vocily.md)\n- [Bolna API + MCP vs Vogent API](https://www.anchorterminal.com/compare/bolna-vs-vogent.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-10", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.4", "openapi": "https://www.anchorterminal.com/openapi.json", "preview": false, "run": "2026-10-01", "runLabel": "October 2026 research run" }, "page": { "breadcrumbs": [ { "name": "Home", "url": "https://www.anchorterminal.com/" }, { "name": "Compare", "url": "https://www.anchorterminal.com/compare/" }, { "name": "AssemblyAI Voice Agent API vs Bolna API + MCP", "url": "" } ], "description": "AssemblyAI Voice Agent scores 64.4 (B) to Bolna's 52.6 (D) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.", "facts": [ "AssemblyAI Voice Agent API B 64.4", "Bolna API + MCP D 52.6", "scores" ], "h1": "AssemblyAI Voice Agent API vs Bolna API + MCP", "image": "https://www.anchorterminal.com/assets/og/compare-assemblyai-voice-agent-vs-bolna.png", "path": "/compare/assemblyai-voice-agent-vs-bolna", "published": "2026-10-01", "section": "tools", "title": "AssemblyAI Voice Agent vs Bolna for AI agents (2026) | Anchor Terminal", "toc": null, "updated": "2026-10-09", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bolna" }, "tokens": { "markdown": 2650, "slim": 730 }, "version": 1 }