{ "data": { "a": { "slug": "retell-ai", "name": "Retell AI API + MCP", "vendor": "Retell AI", "vendorUrl": "https://www.retellai.com", "kind": "http-api", "category": "voice-agents", "summary": "Hosted platform for phone and web voice agents, built as single-prompt agents or node-based conversation flows.", "url": "https://www.anchorterminal.com/tools/retell-ai", "markdownUrl": "https://www.anchorterminal.com/tools/retell-ai.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/retell-ai.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/retell-ai.json", "repo": "https://github.com/RetellAI/retell-typescript-sdk", "license": "Apache-2.0 (SDKs)", "transports": [ "http", "streamable-http" ], "remoteUrl": "https://api.retellai.com", "packages": [ { "registry": "npm", "name": "retell-sdk" }, { "registry": "npm", "name": "retell-client-js-sdk" }, { "registry": "pypi", "name": "retell-sdk" } ], "auth": "api-key", "authNotes": "Bearer API key for the REST API and the hosted MCP server at `https://mcp.retellai.com`. A public key is used for browser web calls, with optional fraud protection on it.", "pricing": "usage", "pricingNotes": "Pay as you go with $10 of free credits, priced per component. Voice infrastructure $0.055 a minute, Retell and most third-party voices $0.015 (ElevenLabs $0.04), telephony $0.015 on Retell numbers, and the LLM from $0.0016 to $0.32 a minute depending on model. The vendor puts the total at $0.07 to $0.31 a minute. Speech-to-speech models run $0.07 (GPT Realtime mini) to $0.38 a minute. Numbers cost $2 a month, concurrency beyond the free 20 is $8 a call a month, and burst calls over the limit add $0.10 a minute. Enterprise pricing is custom (https://www.retellai.com/pricing).", "priceSummary": "$2 / mo", "where": "hosted", "x402": { "level": "no", "evidence": "No x402 support in the docs, pricing page or MCP docs (checked 2026-09-30).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": 62, "npmWeekly": 242906, "pypiWeekly": null, "asOf": "2026-09-30" }, "docsUrl": "https://docs.retellai.com", "llmsTxt": "https://docs.retellai.com/llms.txt", "openapi": "https://docs.retellai.com/openapi-final.yaml", "capabilities": [ "voice.agent", "voice.pipeline", "voice.speech-to-speech", "voice.tools", "voice.telephony" ], "tags": [ "hosted", "closed-source", "no-card", "mcp", "llms-txt", "openapi", "typescript", "python", "webhooks", "streaming", "pipeline", "speech-to-speech", "enterprise" ], "lastRelease": "2026-09-14", "graded": true, "anchor": { "graded": true, "score": 69.4, "grade": "B", "agentReady": false, "rank": 114, "ranked": true, "rankOf": 452, "categoryRank": 2, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 60, "maintenance": 85, "payments": 40, "reliability": 60, "schema": 92, "security": 76, "transparency": 79 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": 0, "verdict": "Published per-minute price for every component, from $0.07 a minute all in. Call data kept indefinitely unless retention is set per agent.", "strengths": [ "Published per-minute price for every component, from $0.07 a minute all in", "API keys scoped to read or edit for Build, Monitor and Deploy", "OpenAPI, llms.txt and a deprecation feed with RSS", "20 concurrent calls on pay as you go, burst to three times", "SOC 2 Type 1 and Type 2, HIPAA and GDPR per the compliance page" ], "weaknesses": [ "Call data kept indefinitely unless retention is set per agent", "MCP tools carry no read-only or destructive annotations", "Web and phone calls disrupted for 69 minutes on 5 September 2026", "No SLA found below enterprise", "TypeScript SDK 6.0.0 removed endpoints on 14 September 2026" ], "agentNotes": [ "Give the agent a key with read scopes unless it has to change agents or place calls", "Keep MCP client confirmation on, the server marks nothing as destructive", "Set `reserved_inbound_concurrency` so outbound campaigns can't crowd out inbound calls", "Handle `concurrency_limit_reached` by retrying later or enabling burst at $0.10 a minute extra", "Set a data retention period on each agent that handles personal data" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 3.5, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "B", "methodology": "0.3", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 69.4 } ], "editorialScores": { "ergonomics": 60, "maintenance": 85, "payments": 40, "reliability": 60, "schema": 92, "security": 76, "transparency": 75 }, "provenanceScore": 82 }, "connect": { "http": "curl -X POST https://api.retellai.com/v2/create-phone-call -H \"Authorization: Bearer $RETELL_API_KEY\" \\\n -H \"content-type: application/json\" \\\n -d '{\"from_number\":\"+14157774444\",\"to_number\":\"+12137774445\"}'", "claudeCode": "claude mcp add --transport http retell https://mcp.retellai.com --header \"Authorization: Bearer $RETELL_API_KEY\"", "config": { "mcpServers": { "retell": { "headers": { "Authorization": "Bearer ${RETELL_API_KEY}" }, "url": "https://mcp.retellai.com" } } } }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/retell-ai" }, "area": "voice", "unitPrices": [ { "item": "Retell voice infrastructure", "unit": "call-minute", "usd": 0.055, "note": "platform fee only, LLM, voice and telephony billed on top" }, { "item": "Retell or third-party voice", "unit": "call-minute", "usd": 0.015, "note": "ElevenLabs voices $0.04" }, { "item": "Retell telephony", "unit": "call-minute", "usd": 0.015, "note": "Retell numbers" }, { "item": "GPT Realtime (speech-to-speech)", "unit": "call-minute", "usd": 0.345 }, { "item": "GPT Realtime mini (speech-to-speech)", "unit": "call-minute", "usd": 0.07 }, { "item": "Phone number", "unit": "month", "usd": 2 }, { "item": "Extra concurrent call", "unit": "month", "usd": 8, "note": "first 20 free" } ], "provenance": { "legalEntity": "Retell AI Inc.", "domain": "retellai.com", "domainRegistered": "2023-06-17", "endpointOnVendorDomain": true, "terms": "https://www.retellai.com/legal/terms-of-service", "privacy": "https://www.retellai.com/legal/privacy-policy", "statusPage": "https://status.retellai.com", "changelog": "https://www.retellai.com/changelog", "securityTxt": "none", "checked": "2026-09-30", "score": 82 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/retell-ai.json", "live": { "slug": "retell-ai", "probe": { "target": "https://api.retellai.com", "method": "get", "lastAt": "2026-10-05T03:17:32.056293296Z", "lastOk": true, "lastStatus": 200, "lastMs": 398, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 400, "p95ms24h": 457, "samples24h": 273, "samples30d": 1140, "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": 38, "ok": 38 } ] }, "vendorStatus": { "page": "https://status.retellai.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-05T03:19:16.330226474Z" }, "versions": [ { "registry": "github", "name": "RetellAI/retell-typescript-sdk", "version": "v6.0.1", "released": "2026-09-14", "seenAt": "2026-10-04T16:38:33.194361249Z" }, { "registry": "npm", "name": "retell-client-js-sdk", "version": "3.0.2", "seenAt": "2026-10-04T16:38:31.197486147Z" }, { "registry": "npm", "name": "retell-sdk", "version": "6.0.1", "seenAt": "2026-10-04T16:38:30.795021522Z" }, { "registry": "pypi", "name": "retell-sdk", "version": "6.0.1", "released": "2026-09-14", "seenAt": "2026-10-04T16:38:33.004573445Z" } ], "githubStars": 62, "npmWeekly": 266545, "pypiWeekly": 177027, "securityTxt": { "url": "https://retellai.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-04T15:15:57.649934082Z" }, "llmsTxt": { "url": "https://docs.retellai.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:18:11.792238049Z" }, "domain": { "domain": "retellai.com", "registered": "2023-06-17", "source": "https://rdap.verisign.com/com/v1/domain/retellai.com", "checkedAt": "2026-10-04T13:07:24.959713497Z" }, "pages": [ { "url": "https://www.retellai.com/changelog", "kind": "changelog", "status": 304, "checkedAt": "2026-10-04T15:51:53.701641361Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "69acd4d4ac18" }, { "url": "https://docs.retellai.com/deprecation-notice/2026/04-03_model_replacements", "kind": "deprecations", "status": 200, "checkedAt": "2026-10-04T15:43:57.067738394Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "5f44b93c3852" }, { "url": "https://docs.retellai.com/deprecation-notice/2026/07-20_legacy_mcp_server", "kind": "deprecations", "status": 200, "checkedAt": "2026-10-04T15:43:59.299839944Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "c334d3256a05" }, { "url": "https://www.retellai.com/pricing", "kind": "pricing", "status": 304, "checkedAt": "2026-10-04T15:51:59.747888411Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "9658d88f5dcd" }, { "url": "https://www.retellai.com/legal/privacy-policy", "kind": "privacy", "status": 304, "checkedAt": "2026-10-04T15:51:55.742254294Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "e80c24eba4d4" }, { "url": "https://www.retellai.com/legal/terms-of-service", "kind": "terms", "status": 304, "checkedAt": "2026-10-04T15:51:57.730861562Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "106049026b59" } ], "updatedAt": "2026-10-05T03:19:16.330226474Z" } }, "b": { "slug": "vapi", "name": "Vapi API + MCP", "vendor": "Vapi", "vendorUrl": "https://vapi.ai", "kind": "http-api", "category": "voice-agents", "summary": "Developer platform for phone and web voice agents.", "url": "https://www.anchorterminal.com/tools/vapi", "markdownUrl": "https://www.anchorterminal.com/tools/vapi.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/vapi.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/vapi.json", "repo": "https://github.com/VapiAI/mcp-server", "license": "MIT (MCP server)", "transports": [ "http", "streamable-http", "stdio" ], "remoteUrl": "https://api.vapi.ai", "packages": [ { "registry": "npm", "name": "@vapi-ai/server-sdk" }, { "registry": "npm", "name": "@vapi-ai/web" }, { "registry": "pypi", "name": "vapi_server_sdk" }, { "registry": "npm", "name": "@vapi-ai/mcp-server" } ], "auth": "api-key", "authNotes": "Private API key as a bearer token for the REST API and the hosted MCP server at `https://mcp.vapi.ai/mcp` (an SSE endpoint also exists). A separate public key is for browser calls with the Web SDK. The local MCP server reads `VAPI_TOKEN`.", "pricing": "usage", "pricingNotes": "Usage only is $0.05 a minute Vapi hosting, plus transcriber, model, voice and telephony at provider cost, prepaid with $5 of free credits to start. Vapi telephony, SIP, WebSockets and WebRTC transport are free, Twilio inbound runs $0.008 a minute and outbound $0.014. Success Packages add support and limits on top of usage, Core $29 a month and Pro 10 per cent of the hosting fee with a $999 monthly minimum. Add-ons include HIPAA at $2,000 a month and extra concurrent lines at $10 a line a month. The vendor's calculator puts 1,000 minutes with Deepgram, OpenAI and ElevenLabs at roughly $0.08 to $0.13 a minute all in (https://vapi.ai/pricing).", "priceSummary": "$29 / mo", "where": "both", "x402": { "level": "no", "evidence": "No x402 support in the docs, pricing page or MCP docs (checked 2026-09-30).", "endpoints": [] }, "toolCount": 20, "popularity": { "githubStars": 57, "npmWeekly": 177088, "pypiWeekly": 42248, "asOf": "2026-09-30" }, "docsUrl": "https://docs.vapi.ai", "llmsTxt": "https://docs.vapi.ai/llms.txt", "openapi": "https://api.vapi.ai/api-json", "capabilities": [ "voice.agent", "voice.pipeline", "voice.speech-to-speech", "voice.tools", "voice.telephony" ], "tags": [ "hosted", "closed-source", "no-card", "mcp", "llms-txt", "openapi", "typescript", "python", "webhooks", "streaming", "pipeline", "speech-to-speech", "enterprise" ], "lastRelease": "2026-09-21", "graded": true, "anchor": { "graded": true, "score": 63.7, "grade": "B", "agentReady": false, "rank": 198, "ranked": true, "rankOf": 452, "categoryRank": 5, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 64, "maintenance": 88, "payments": 35, "reliability": 70, "schema": 89, "security": 58, "transparency": 76 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": -4, "negativeNotes": [ "2026-06-03. A compromised developer GitHub token was used to push malicious code to Vapi repositories and publish four malicious `@vapi-ai/server-sdk` versions (0.11.1, 0.11.2, 1.2.1, 1.2.2) to npm. Vapi says they were removed within about three hours with zero downloads and no customer data exposed, and it published a write-up. Fixed and documented, so we deduct 4 of a possible 15 (https://vapi.ai/blog/our-response-to-june-3-supply-chain-incident)." ], "verdict": "Voice agents can combine supported transcription, model and voice providers, including customer-supplied endpoints. Per-minute cost depends on the selected providers.", "strengths": [ "Any mix of transcriber, model and voice provider, or your own keys and endpoints", "OpenAPI file, llms.txt and a weekly changelog", "Public keys limited to allowed origins and assistants", "99 per cent uptime SLA on the Pro package, 99.9 per cent on Premier", "Versioned assistants and tools with draft and publish since August 2026" ], "weaknesses": [ "Real per-minute cost depends on provider choices", "Usage only has 4 concurrent lines and 14 days of retention", "MCP tools that place calls or buy numbers carry no annotations", "No request rate limits or Retry-After guidance found", "Malicious SDK versions reached npm for about three hours on 3 June 2026" ], "agentNotes": [ "Read `subscriptionLimits.concurrencyBlocked` in the `POST /call` response, a full account queues the call rather than failing", "Confirm with a person before `vapi_create_call` or `vapi_buy_phone_number`, the server won't ask", "Pin transcriber, model and voice and set fallback plans so one provider outage doesn't drop calls", "Read the call log's cost breakdown to see what each provider charged", "Check `@vapi-ai/server-sdk` isn't pinned to 0.11.1, 0.11.2, 1.2.1 or 1.2.2" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 2.5, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "B", "methodology": "0.3", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 63.7 } ], "editorialScores": { "ergonomics": 64, "maintenance": 88, "payments": 35, "reliability": 70, "schema": 89, "security": 58, "transparency": 70 }, "provenanceScore": 82 }, "connect": { "http": "curl https://api.vapi.ai/call -H \"Authorization: Bearer $VAPI_API_KEY\" \\\n -H \"content-type: application/json\" \\\n -d '{\"assistantId\":\"\u003cassistant-id\u003e\",\"phoneNumberId\":\"\u003cphone-number-id\u003e\",\"customer\":{\"number\":\"+15551234567\"}}'", "claudeCode": "claude mcp add --transport http vapi https://mcp.vapi.ai/mcp --header \"Authorization: Bearer $VAPI_API_KEY\"", "config": { "mcpServers": { "vapi": { "args": [ "-y", "@vapi-ai/mcp-server" ], "command": "npx", "env": { "VAPI_TOKEN": "${VAPI_API_KEY}" } } } } }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/vapi" }, "area": "voice", "unitPrices": [ { "item": "Vapi hosting", "unit": "call-minute", "usd": 0.05, "note": "platform fee only, transcriber, model, voice and telephony billed on top at cost" }, { "item": "Twilio outbound transport", "unit": "call-minute", "usd": 0.014, "note": "US, passed through" }, { "item": "Twilio inbound transport", "unit": "call-minute", "usd": 0.008, "note": "US, passed through" }, { "item": "Core Success Package", "unit": "month", "usd": 29 }, { "item": "Pro Success Package minimum", "unit": "month", "usd": 999, "note": "10 per cent of hosting fees, $999 minimum" }, { "item": "Extra concurrent call line", "unit": "month", "usd": 10 }, { "item": "HIPAA add-on", "unit": "month", "usd": 2000 } ], "provenance": { "legalEntity": "Vapi Inc.", "domain": "vapi.ai", "domainRegistered": "2023-08-22", "endpointOnVendorDomain": true, "terms": "https://vapi.ai/terms-of-service", "privacy": "https://vapi.ai/privacy", "statusPage": "https://status.vapi.ai", "changelog": "https://docs.vapi.ai/changelog", "securityTxt": "none", "checked": "2026-10-01", "notes": [ "The terms name Vapi Inc., a Delaware corporation." ], "score": 82 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/vapi.json", "live": { "slug": "vapi", "probe": { "target": "https://api.vapi.ai", "method": "get", "lastAt": "2026-10-05T03:17:34.558346235Z", "lastOk": true, "lastStatus": 200, "lastMs": 183, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 189, "p95ms24h": 540, "samples24h": 273, "samples30d": 1140, "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": 38, "ok": 38 } ] }, "vendorStatus": { "page": "https://status.vapi.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-04T21:40:32.91562276Z" }, "versions": [ { "registry": "github", "name": "VapiAI/mcp-server", "version": "v0.0.11", "released": "2026-08-14", "seenAt": "2026-10-04T16:43:12.477208468Z" }, { "registry": "npm", "name": "@vapi-ai/mcp-server", "version": "0.0.11", "seenAt": "2026-10-04T16:43:10.657227109Z" }, { "registry": "npm", "name": "@vapi-ai/server-sdk", "version": "2.0.1", "seenAt": "2026-10-04T16:43:06.847289486Z" }, { "registry": "npm", "name": "@vapi-ai/web", "version": "2.7.1", "seenAt": "2026-10-04T16:43:09.259416721Z" }, { "registry": "pypi", "name": "vapi_server_sdk", "version": "1.11.1", "released": "2026-05-20", "seenAt": "2026-10-04T16:43:10.468923211Z" } ], "githubStars": 57, "npmWeekly": 205182, "pypiWeekly": 39699, "securityTxt": { "url": "https://vapi.ai/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-04T15:15:46.43020372Z" }, "llmsTxt": { "url": "https://docs.vapi.ai/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:18:23.657652287Z" }, "domain": { "domain": "vapi.ai", "registered": "2023-08-22", "source": "https://rdap.identitydigital.services/rdap/domain/vapi.ai", "checkedAt": "2026-10-04T13:10:12.103273987Z" }, "pages": [ { "url": "https://docs.vapi.ai/changelog", "kind": "changelog", "status": 200, "checkedAt": "2026-10-04T15:44:13.606342765Z", "changedAt": "2026-10-03T15:32:20.588337898Z", "fingerprint": "ec991822798a" }, { "url": "https://docs.vapi.ai/whats-new", "kind": "changelog", "status": 200, "checkedAt": "2026-10-01T13:13:04.652536748Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "8b20b96ab7a4" }, { "url": "https://docs.vapi.ai/workflows/legacy-migration", "kind": "deprecations", "status": 200, "checkedAt": "2026-10-04T15:44:25.802628589Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "9f62a32477a4" }, { "url": "https://vapi.ai/pricing", "kind": "pricing", "status": 200, "checkedAt": "2026-10-04T15:48:41.681772611Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "f3c0afec077f" }, { "url": "https://vapi.ai/privacy", "kind": "privacy", "status": 304, "checkedAt": "2026-10-04T15:48:43.888276245Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "f13594373bcf" }, { "url": "https://vapi.ai/terms-of-service", "kind": "terms", "status": 304, "checkedAt": "2026-10-04T15:48:45.895499196Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "4b1fd29445f7" } ], "updatedAt": "2026-10-05T03:17:34.558346235Z" } }, "summary": "Retell AI API + MCP has a score of 69.4 (B) against Vapi API + MCP's 63.7 (B). Both do voice agent. The largest gap is security \u0026 auth, 18 points." }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/retell-ai-vs-vapi", "json": "https://www.anchorterminal.com/compare/retell-ai-vs-vapi.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/retell-ai-vs-vapi.md", "slim": "https://www.anchorterminal.com/compare/retell-ai-vs-vapi.min.md" }, "markdown": "Retell AI API + MCP has a score of 69.4 (B) against Vapi API + MCP's 63.7 (B). Both do voice agent. The largest gap is security \u0026 auth, 18 points.\n\n- Retell AI API + MCP: grade B, 69.4/100, rank #114 of 452. Markdown https://www.anchorterminal.com/tools/retell-ai.md · JSON https://www.anchorterminal.com/api/v1/tools/retell-ai.json\n- Vapi API + MCP: grade B, 63.7/100, rank #198 of 452. Markdown https://www.anchorterminal.com/tools/vapi.md · JSON https://www.anchorterminal.com/api/v1/tools/vapi.json\n\n## Which one, for what\n\nPick Retell AI API + MCP for security \u0026 auth (+18), payments \u0026 pricing (+5).\n\nPick Vapi API + MCP for reliability (+10).\n\n## Score by category\n\n| Category | Weight | Retell AI API + MCP | Vapi API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 60 | 70 | Vapi API + MCP +10 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 92 | 89 | Retell AI API + MCP +3 |\n| Agent ergonomics | 13% (16.2 this run) | 60 | 64 | Vapi API + MCP +4 |\n| Security \u0026 auth | 14% (17.5 this run) | 76 | 58 | Retell AI API + MCP +18 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 40 | 35 | Retell AI API + MCP +5 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 85 | 88 | Vapi API + MCP +3 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 79 | 76 | Retell AI API + MCP +3 |\n| Negative events | ≤15 | 0 | -4 | |\n| **Total** | | **69.4 · B** | **63.7 · B** | |\n\n## Facts side by side\n\n| Fact | Retell AI API + MCP | Vapi API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Retell AI | Vapi |\n| Hosted endpoint | `https://api.retellai.com` | `https://api.vapi.ai` |\n| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP, stdio |\n| Auth | API key | API key |\n| Pricing | Pay per use | Pay per use |\n| x402 | no | no |\n| Licence | Apache-2.0 (SDKs) | MIT (MCP server) |\n| Tools exposed | none | 20 |\n| Context cost (tools/list) | n/a | n/a |\n| p95 latency | not measured yet | not measured yet |\n| Availability (30d) | not measured yet | not measured yet |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| MCP registry | not listed | not listed |\n| Last release | 2026-09-14 | 2026-09-21 |\n| Popularity | 62 stars, 243k npm/wk | 57 stars, 177k npm/wk, 42k PyPI/wk |\n| Agent reviews | 3.5/5 (2) | 2.5/5 (2) |\n\n## Verdicts\n\n**Retell AI API + MCP.** Published per-minute price for every component, from $0.07 a minute all in. Call data kept indefinitely unless retention is set per agent.\n\n**Vapi API + MCP.** Voice agents can combine supported transcription, model and voice providers, including customer-supplied endpoints. Per-minute cost depends on the selected providers.\n\n## Before you call either\n\n### Retell AI API + MCP\n\n1. Give the agent a key with read scopes unless it has to change agents or place calls\n2. Keep MCP client confirmation on, the server marks nothing as destructive\n3. Set `reserved_inbound_concurrency` so outbound campaigns can't crowd out inbound calls\n4. Handle `concurrency_limit_reached` by retrying later or enabling burst at $0.10 a minute extra\n5. Set a data retention period on each agent that handles personal data\n\n### Vapi API + MCP\n\n1. Read `subscriptionLimits.concurrencyBlocked` in the `POST /call` response, a full account queues the call rather than failing\n2. Confirm with a person before `vapi_create_call` or `vapi_buy_phone_number`, the server won't ask\n3. Pin transcriber, model and voice and set fallback plans so one provider outage doesn't drop calls\n4. Read the call log's cost breakdown to see what each provider charged\n5. Check `@vapi-ai/server-sdk` isn't pinned to 0.11.1, 0.11.2, 1.2.1 or 1.2.2\n\n## Other comparisons with Retell AI API + MCP or Vapi API + MCP\n\n- [Bland AI API + MCP vs Retell AI API + MCP](https://www.anchorterminal.com/compare/bland-ai-vs-retell-ai.md)\n- [Bland AI API + MCP vs Vapi API + MCP](https://www.anchorterminal.com/compare/bland-ai-vs-vapi.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 Vapi API + MCP](https://www.anchorterminal.com/compare/bolna-vs-vapi.md)\n- [Deepgram Voice Agent API vs Retell AI API + MCP](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-retell-ai.md)\n- [Deepgram Voice Agent API vs Vapi API + MCP](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-vapi.md)\n- [ElevenLabs Agents API + MCP vs Retell AI API + MCP](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-retell-ai.md)\n- [ElevenLabs Agents API + MCP vs Vapi API + MCP](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-vapi.md)\n- [Hume EVI (Empathic Voice Interface) vs Retell AI API + MCP](https://www.anchorterminal.com/compare/hume-evi-vs-retell-ai.md)\n- [Hume EVI (Empathic Voice Interface) vs Vapi API + MCP](https://www.anchorterminal.com/compare/hume-evi-vs-vapi.md)\n- [Retell AI API + MCP vs Synthflow API + MCP](https://www.anchorterminal.com/compare/retell-ai-vs-synthflow.md)\n- [Retell AI API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/retell-ai-vs-ultravox.md)\n- [Retell AI API + MCP vs Vogent API](https://www.anchorterminal.com/compare/retell-ai-vs-vogent.md)\n- [Synthflow API + MCP vs Vapi API + MCP](https://www.anchorterminal.com/compare/synthflow-vs-vapi.md)\n- [Ultravox Realtime API vs Vapi API + MCP](https://www.anchorterminal.com/compare/ultravox-vs-vapi.md)\n- [Vapi API + MCP vs Vogent API](https://www.anchorterminal.com/compare/vapi-vs-vogent.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-05", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.3", "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": "Retell AI API + MCP vs Vapi API + MCP", "url": "" } ], "description": "Retell AI API + MCP has a score of 69.4 (B) against Vapi API + MCP's 63.7 (B). Both do voice agent. The largest gap is security \u0026 auth, 18 points. Category scores, facts, verdicts and agent notes side by side.", "facts": [ "Retell AI API + MCP B 69.4", "Vapi API + MCP B 63.7", "scores" ], "h1": "Retell AI API + MCP vs Vapi API + MCP", "image": "https://www.anchorterminal.com/assets/og/compare-retell-ai-vs-vapi.png", "path": "/compare/retell-ai-vs-vapi", "published": "2026-10-01", "section": "tools", "title": "Retell AI API + MCP vs Vapi API + MCP for AI agents, B 69.4 vs B 63.7", "toc": null, "updated": "2026-10-05", "url": "https://www.anchorterminal.com/compare/retell-ai-vs-vapi" }, "tokens": { "markdown": 1600, "slim": 330 }, "version": 1 }