{ "data": { "a": { "slug": "gemini-live", "name": "Gemini Live API", "vendor": "Google", "vendorUrl": "https://ai.google.dev", "kind": "http-api", "category": "voice-agents", "summary": "Google's Live API runs real-time spoken conversations with Gemini audio-to-audio models over a stateful WebSocket. It takes audio, images and text, speaks back, and supports interruptions, function calling and Google Search grounding.", "url": "https://www.anchorterminal.com/tools/gemini-live", "markdownUrl": "https://www.anchorterminal.com/tools/gemini-live.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/gemini-live.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/gemini-live.json", "repo": "https://github.com/google-gemini/gemini-live-api-examples", "license": "Proprietary service under the Gemini API Additional Terms of Service. The Python and JavaScript SDKs are Apache-2.0", "transports": [ "http" ], "remoteUrl": "https://generativelanguage.googleapis.com/v1beta", "packages": [ { "registry": "pypi", "name": "google-genai" }, { "registry": "npm", "name": "@google/genai" } ], "auth": "api-key", "authNotes": "Self-serve API key from Google AI Studio, tied to a Google Cloud project. Keys created since 28 May 2026 are authorisation keys bound to a service account and restricted to the Gemini API, and unrestricted standard keys are rejected. The raw WebSocket guide passes the key as a `key` query parameter. For browsers and phones, a backend mints an ephemeral token (preview) at `POST /v1beta/auth_tokens`, single use by default, 1 minute to start a session and 30 minutes to use it, optionally locked to a model and configuration.", "pricing": "freemium", "pricingNotes": "Free tier on the Live models with no billing account, where content is used to improve Google products. Paid tier per 1M tokens on `gemini-3.8-live`, the extended thinking model and `gemini-3.1-flash-live-preview`. Text in $0.75, audio in $3.00 (about $0.005 a minute), image or video in $1.00, text out $4.50, audio out $12.00 (about $0.018 a minute). Google Search grounding $14 per 1,000 queries after 5,000 free a month. Each turn re-bills the whole session context. Paid tier needs a linked billing account and a $5 minimum prepayment (https://ai.google.dev/gemini-api/docs/pricing, checked 2026-10-08).", "priceSummary": "$14 / 1k req", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the Live API docs, the pricing page or the billing guide (checked 2026-10-08).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": null, "npmWeekly": 29486957, "pypiWeekly": 34128301, "asOf": "2026-10-08" }, "docsUrl": "https://ai.google.dev/gemini-api/docs/live-api", "llmsTxt": "https://ai.google.dev/gemini-api/docs/llms.txt", "capabilities": [ "voice.agent", "voice.speech-to-speech", "voice.tools" ], "tags": [ "hosted", "freemium", "free-tier", "closed-source", "speech-to-speech", "websocket", "streaming", "python", "typescript", "llms-txt", "api-key", "function-calling" ], "lastRelease": "2026-09-15", "graded": true, "anchor": { "graded": true, "score": 57.1, "grade": "C", "agentReady": false, "rank": 560, "ranked": true, "rankOf": 842, "categoryRank": 7, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 69, "maintenance": 83, "payments": 40, "reliability": 41, "schema": 66, "security": 48, "transparency": 72 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-08" }, "negative": 0, "verdict": "A speech-to-speech API with per-token prices published, a free tier and a generally available model, `gemini-3.8-live`, since 15 September 2026. The documented raw WebSocket connection carries the API key in the URL, connections reset about every 10 minutes, and no SLA or readable incident history was found for the Developer API.", "bestFor": "Teams building their own voice or vision assistant on a single speech-to-speech model with function calling and Search grounding, who can run a backend for tokens and audio transport.", "strengths": [ "`gemini-3.8-live` went generally available on 15 September 2026 with asynchronous function calling as the default and three response scheduling modes.", "Ephemeral tokens can be single use, expire in 30 minutes by default and be locked to a model and session configuration.", "Prices are public per million tokens with per-minute equivalents, $0.005 a minute of audio in and $0.018 a minute of audio out.", "Session resumption handles, a GoAway message with `timeLeft` and sliding-window context compression are documented for long sessions.", "Free tier on the Live models with no billing account, and paid-tier content isn't used to improve Google products per the pricing page." ], "weaknesses": [ "The WebSocket guide authenticates with the API key as a `key` query parameter, and ephemeral tokens as an `access_token` query parameter.", "The status page at aistudio.google.com/status renders in the browser only, so no incident history could be read, and no SLA was found for the Developer API.", "No machine-readable contract for the WebSocket messages was found. The Discovery document types only the setup and token schemas.", "The capabilities, best practices and API reference pages still say the Live API is in preview, and the docs give both 70 and 99 supported languages.", "No telephony. Phone calls need a partner such as Voximplant, LiveKit or Pipecat, and concurrent session limits are shown only inside AI Studio." ], "agentNotes": [ "Enable `sessionResumption` and keep the newest handle. Connections end after about 10 minutes, and handles stay valid for 2 hours.", "Set `contextWindowCompression` with a sliding window. Without it audio sessions stop at 15 minutes and audio with video at 2 minutes, and every turn re-bills the whole context.", "On `gemini-3.8-live` function calls are non-blocking by default. Set `behavior: BLOCKING` if the model must wait for the tool response.", "Send 16 kHz 16-bit PCM in 20 to 40 ms chunks and discard buffered playback when `interrupted` is true.", "Keep the API key on a server and send it through the SDK. Give browsers an ephemeral token from `POST /v1beta/auth_tokens`, locked with `liveConnectConstraints`." ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 57.1 } ], "editorialScores": { "ergonomics": 69, "maintenance": 83, "payments": 40, "reliability": 41, "schema": 66, "security": 48, "transparency": 55 }, "provenanceScore": 89 }, "connect": { "install": "pip install google-genai # or: npm i @google/genai", "http": "curl -X POST \"https://generativelanguage.googleapis.com/v1beta/auth_tokens\" \\\n -H \"x-goog-api-key: $GEMINI_API_KEY\" -H \"Content-Type: application/json\" \\\n -d '{\"uses\": 1, \"liveConnectConstraints\": {\"model\": \"models/gemini-3.8-live\", \"config\": {\"sessionResumption\": {}, \"responseModalities\": [\"AUDIO\"]}}}'" }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/gemini-live" }, "sameCompany": [ "gemini-api", "gemini-embedding", "vertex-ai-tuning", "google-model-armor", "google-imagen", "google-veo", "google-lyria", "google-speech-to-text", "google-adk", "google-secret-manager", "google-weather-api", "chrome-devtools-mcp", "google-maps-platform", "google-cloud-translation", "google-calendar-api", "firebase-cloud-messaging", "google-drive-api", "gemini-cli", "google-search-console", "google-ads-api", "google-forms", "google-sheets-api", "gmail-api" ], "area": "voice", "unitPrices": [ { "item": "gemini-3.8-live audio input", "unit": "audio-minute", "usd": 0.005, "note": "$3.00 per 1M audio tokens, charged while the API is listening" }, { "item": "gemini-3.8-live audio output", "unit": "audio-minute", "usd": 0.018, "note": "$12.00 per 1M audio tokens" }, { "item": "gemini-3.8-live text input", "unit": "1m-tokens", "usd": 0.75 }, { "item": "gemini-3.8-live text output", "unit": "1m-tokens", "usd": 4.5, "note": "includes thinking tokens and transcription text" }, { "item": "Google Search grounding", "unit": "1k-requests", "usd": 14, "note": "after 5,000 free search queries a month shared across Gemini 3.x models" } ], "provenance": { "legalEntity": "Google LLC", "domain": "google.com", "domainRegistered": "1997-09-15", "endpointOnVendorDomain": true, "terms": "https://ai.google.dev/gemini-api/terms", "privacy": "https://policies.google.com/privacy", "statusPage": "https://aistudio.google.com/status", "changelog": "https://ai.google.dev/gemini-api/docs/changelog", "securityTxt": "valid", "checked": "2026-10-08", "notes": [ "The WebSocket and the token endpoint are on generativelanguage.googleapis.com, Google's API domain. The docs are on ai.google.dev.", "RDAP for google.com gives a registration date of 1997-09-15.", "The Gemini API Additional Terms of Service are effective 23 March 2026 and incorporate the Google APIs Terms of Service. Paid services fall under Google's Data Processing Addendum for products where Google is a data processor.", "The Google Privacy Policy read on 8 October 2026 is effective 1 October 2026. It is Google's general policy, and the terms page is where API data use is set out.", "www.google.com/.well-known/security.txt expires 2030-04-01 and points to g.co/vulnz and the vulnerability reward programme. ai.google.dev has no security.txt of its own (404).", "aistudio.google.com/status answered 200 with a page drawn by script, so no component or incident history was read." ], "score": 89 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/gemini-live.json", "live": { "slug": "gemini-live", "probe": { "target": "https://generativelanguage.googleapis.com/v1beta", "method": "get", "lastAt": "2026-10-09T11:46:29.256413354Z", "lastOk": true, "lastStatus": 404, "lastMs": 12, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 24, "p95ms24h": 48, "samples24h": 44, "samples30d": 44, "days": [ { "date": "2026-10-09", "probes": 44, "ok": 44 } ] }, "updatedAt": "2026-10-09T11:46:29.256413354Z" } }, "answer": "Retell AI API + MCP scores 69.1 (B) on agent readiness against Gemini Live API's 57.1 (C), and leads in 5 of 7 scored categories. Gemini Live API leads on agent ergonomics.", "b": { "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": 69.1, "grade": "B", "agentReady": false, "rank": 187, "ranked": true, "rankOf": 842, "categoryRank": 2, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 60, "maintenance": 85, "payments": 40, "reliability": 60, "schema": 92, "security": 76, "transparency": 76 }, "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.", "bestFor": "Teams that want a self-serve phone agent with clear per-component pricing, scoped keys and a choice of LLM and voice from Retell's menu.", "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": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 69.1 } ], "editorialScores": { "ergonomics": 60, "maintenance": 85, "payments": 40, "reliability": 60, "schema": 92, "security": 76, "transparency": 75 }, "provenanceScore": 76 }, "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": 76 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/retell-ai.json", "live": { "slug": "retell-ai", "probe": { "target": "https://api.retellai.com", "method": "get", "lastAt": "2026-10-09T11:46:38.907451531Z", "lastOk": true, "lastStatus": 200, "lastMs": 424, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 408, "p95ms24h": 478, "samples24h": 259, "samples30d": 2311, "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": 125, "ok": 125 } ] }, "vendorStatus": { "page": "https://status.retellai.com", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-09T11:40:31.38936833Z" }, "versions": [ { "registry": "github", "name": "RetellAI/retell-typescript-sdk", "version": "v6.2.4", "released": "2026-10-08", "seenAt": "2026-10-08T16:27:39.051725293Z" }, { "registry": "npm", "name": "retell-client-js-sdk", "version": "3.0.2", "seenAt": "2026-10-08T16:27:37.515726647Z" }, { "registry": "npm", "name": "retell-sdk", "version": "6.2.4", "seenAt": "2026-10-08T16:27:36.694358813Z" }, { "registry": "pypi", "name": "retell-sdk", "version": "6.2.4", "released": "2026-10-08", "seenAt": "2026-10-08T16:27:38.901416818Z" } ], "githubStars": 62, "npmWeekly": 267235, "pypiWeekly": 173116, "securityTxt": { "url": "https://retellai.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-08T15:38:40.083802727Z" }, "llmsTxt": { "url": "https://docs.retellai.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-08T14:00:50.27396215Z" }, "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": 200, "checkedAt": "2026-10-08T18:29:56.954961748Z", "changedAt": "2026-10-08T18:29:56.954961748Z", "fingerprint": "7df19ab9dc8f" }, { "url": "https://docs.retellai.com/deprecation-notice/2026/04-03_model_replacements", "kind": "deprecations", "status": 200, "checkedAt": "2026-10-08T18:19:20.315774064Z", "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": "2026-10-08T18:19:23.694203981Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "c334d3256a05" }, { "url": "https://www.retellai.com/pricing", "kind": "pricing", "status": 200, "checkedAt": "2026-10-08T18:30:03.160306453Z", "changedAt": "2026-10-08T18:30:03.160306453Z", "fingerprint": "c1f1fb60611d" }, { "url": "https://www.retellai.com/legal/privacy-policy", "kind": "privacy", "status": 200, "checkedAt": "2026-10-08T18:29:59.030163173Z", "changedAt": "2026-10-08T18:29:59.030163173Z", "fingerprint": "ebd85c5576c1" }, { "url": "https://www.retellai.com/legal/terms-of-service", "kind": "terms", "status": 200, "checkedAt": "2026-10-08T18:30:01.074364449Z", "changedAt": "2026-10-08T18:30:01.074364449Z", "fingerprint": "a7f4826d8c6e" } ], "updatedAt": "2026-10-09T11:46:38.907451531Z" } }, "facts": [ { "a": "HTTP API", "b": "HTTP API", "name": "Kind" }, { "a": "Google", "b": "Retell AI", "name": "Vendor" }, { "a": "https://generativelanguage.googleapis.com/v1beta", "b": "https://api.retellai.com", "name": "Hosted endpoint" }, { "a": "HTTP", "b": "HTTP, Streamable HTTP", "name": "Transports" }, { "a": "API key", "b": "API key", "name": "Auth" }, { "a": "Freemium", "b": "Pay per use", "name": "Pricing" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "Proprietary service under the Gemini API Additional Terms of Service. The Python and JavaScript SDKs are Apache-2.0", "b": "Apache-2.0 (SDKs)", "name": "Licence" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "yes", "name": "llms.txt" }, { "a": "2026-09-15", "b": "2026-09-14", "name": "Last release" }, { "a": "2026-04-28", "b": "2026-06-01", "name": "Terms last updated" }, { "a": "2026-10-01", "b": "2026-07-20", "name": "Privacy policy last updated" }, { "a": "yes", "b": "yes, with an opt-out", "name": "Customer content may train models" }, { "a": "yes", "b": "yes", "name": "Terms restrict automated access" }, { "a": "yes", "b": "yes", "name": "Terms restrict benchmarking" }, { "a": "not found in the text", "b": "not found in the text", "name": "Terms or service can change without notice" }, { "a": "not found in the text", "b": "yes", "name": "Arbitration or class-action waiver" }, { "a": "29.5M npm/wk, 34.1M PyPI/wk", "b": "62 stars, 243k npm/wk", "name": "Popularity" }, { "a": "none", "b": "3.5/5 (2)", "name": "Agent reviews" } ], "faq": [ { "answer": "Retell AI API + MCP scores 69.1 (B) on agent readiness against Gemini Live API's 57.1 (C), and leads in 5 of 7 scored categories. Gemini Live API leads on agent ergonomics.", "question": "Which is better for AI agents, Gemini Live API or Retell AI API + MCP?" }, { "answer": "Both need an API key.", "question": "Do Gemini Live API and Retell AI API + MCP need an API key?" }, { "answer": "Yes. Gemini Live API has a hosted endpoint at https://generativelanguage.googleapis.com/v1beta and Retell AI API + MCP at https://api.retellai.com.", "question": "Can an agent call Gemini Live API and Retell AI API + MCP without installing anything?" } ], "goodFor": [ { "aheadOn": [ "Agent ergonomics, 69 against 60" ], "also": null, "goodFor": "Teams building their own voice or vision assistant on a single speech-to-speech model with function calling and Search grounding, who can run a backend for tokens and audio transport.", "slug": "gemini-live", "watchFor": "The WebSocket guide authenticates with the API key as a `key` query parameter, and ephemeral tokens as an `access_token` query parameter." }, { "aheadOn": [ "Reliability, 60 against 41", "Schema \u0026 documentation, 92 against 66", "Security \u0026 auth, 76 against 48" ], "also": [ "Free to start without a card" ], "goodFor": "Teams that want a self-serve phone agent with clear per-component pricing, scoped keys and a choice of LLM and voice from Retell's menu.", "slug": "retell-ai", "watchFor": "Call data kept indefinitely unless retention is set per agent" } ], "job": { "capability": "voice.agent", "name": "Voice agent" }, "others": [ { "json": "https://www.anchorterminal.com/compare/bland-ai-vs-gemini-live.json", "title": "Bland AI API + MCP vs Gemini Live API", "url": "https://www.anchorterminal.com/compare/bland-ai-vs-gemini-live" }, { "json": "https://www.anchorterminal.com/compare/bland-ai-vs-retell-ai.json", "title": "Bland AI API + MCP vs Retell AI API + MCP", "url": "https://www.anchorterminal.com/compare/bland-ai-vs-retell-ai" }, { "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-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/deepgram-voice-agent-vs-gemini-live.json", "title": "Deepgram Voice Agent API vs Gemini Live API", "url": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-gemini-live" }, { "json": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-retell-ai.json", "title": "Deepgram Voice Agent API vs Retell AI API + MCP", "url": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-retell-ai" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-gemini-live.json", "title": "ElevenLabs Agents API + MCP vs Gemini Live API", "url": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-gemini-live" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-retell-ai.json", "title": "ElevenLabs Agents API + MCP vs Retell AI API + MCP", "url": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-retell-ai" }, { "json": "https://www.anchorterminal.com/compare/gemini-live-vs-hume-evi.json", "title": "Gemini Live API vs Hume EVI (Empathic Voice Interface)", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-hume-evi" }, { "json": "https://www.anchorterminal.com/compare/gemini-live-vs-synthflow.json", "title": "Gemini Live API vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-synthflow" }, { "json": "https://www.anchorterminal.com/compare/gemini-live-vs-ultravox.json", "title": "Gemini Live API vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/gemini-live-vs-vapi.json", "title": "Gemini Live API vs Vapi API + MCP", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-vapi" }, { "json": "https://www.anchorterminal.com/compare/gemini-live-vs-vocily.json", "title": "Gemini Live API vs Vocily AI", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-vocily" }, { "json": "https://www.anchorterminal.com/compare/gemini-live-vs-vogent.json", "title": "Gemini Live API vs Vogent API", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-vogent" }, { "json": "https://www.anchorterminal.com/compare/hume-evi-vs-retell-ai.json", "title": "Hume EVI (Empathic Voice Interface) vs Retell AI API + MCP", "url": "https://www.anchorterminal.com/compare/hume-evi-vs-retell-ai" }, { "json": "https://www.anchorterminal.com/compare/retell-ai-vs-synthflow.json", "title": "Retell AI API + MCP vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/retell-ai-vs-synthflow" }, { "json": "https://www.anchorterminal.com/compare/retell-ai-vs-ultravox.json", "title": "Retell AI API + MCP vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/retell-ai-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/retell-ai-vs-vapi.json", "title": "Retell AI API + MCP vs Vapi API + MCP", "url": "https://www.anchorterminal.com/compare/retell-ai-vs-vapi" }, { "json": "https://www.anchorterminal.com/compare/retell-ai-vs-vocily.json", "title": "Retell AI API + MCP vs Vocily AI", "url": "https://www.anchorterminal.com/compare/retell-ai-vs-vocily" }, { "json": "https://www.anchorterminal.com/compare/retell-ai-vs-vogent.json", "title": "Retell AI API + MCP vs Vogent API", "url": "https://www.anchorterminal.com/compare/retell-ai-vs-vogent" } ], "scores": [ { "by": 19, "edge": "retell-ai", "gemini-live": 41, "key": "reliability", "name": "Reliability", "retell-ai": 60, "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 26, "edge": "retell-ai", "gemini-live": 66, "key": "schema", "name": "Schema \u0026 documentation", "retell-ai": 92, "weight": 13 }, { "by": 9, "edge": "gemini-live", "gemini-live": 69, "key": "ergonomics", "name": "Agent ergonomics", "retell-ai": 60, "weight": 13 }, { "by": 28, "edge": "retell-ai", "gemini-live": 48, "key": "security", "name": "Security \u0026 auth", "retell-ai": 76, "weight": 14 }, { "by": 0, "edge": "", "gemini-live": 40, "key": "payments", "name": "Payments \u0026 pricing", "retell-ai": 40, "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 2, "edge": "retell-ai", "gemini-live": 83, "key": "maintenance", "name": "Maintenance \u0026 community", "retell-ai": 85, "weight": 7 }, { "by": 4, "edge": "retell-ai", "gemini-live": 72, "key": "transparency", "name": "Transparency \u0026 trust", "retell-ai": 76, "weight": 7 } ], "summary": "Retell AI API + MCP scores 69.1 (B) on agent readiness against Gemini Live API's 57.1 (C), and leads in 5 of 7 scored categories. Gemini Live API leads on agent ergonomics. Both do voice agent.", "verdicts": { "gemini-live": "A speech-to-speech API with per-token prices published, a free tier and a generally available model, `gemini-3.8-live`, since 15 September 2026. The documented raw WebSocket connection carries the API key in the URL, connections reset about every 10 minutes, and no SLA or readable incident history was found for the Developer API.", "retell-ai": "Published per-minute price for every component, from $0.07 a minute all in. Call data kept indefinitely unless retention is set per agent." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/gemini-live-vs-retell-ai", "json": "https://www.anchorterminal.com/compare/gemini-live-vs-retell-ai.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/gemini-live-vs-retell-ai.md", "slim": "https://www.anchorterminal.com/compare/gemini-live-vs-retell-ai.min.md" }, "markdown": "Retell AI API + MCP scores 69.1 (B) on agent readiness against Gemini Live API's 57.1 (C), and leads in 5 of 7 scored categories. Gemini Live API leads on agent ergonomics. Both do voice agent.\n\n- Gemini Live API: grade C, 57.1/100, rank #560 of 842. Markdown https://www.anchorterminal.com/tools/gemini-live.md · JSON https://www.anchorterminal.com/api/v1/tools/gemini-live.json\n- Retell AI API + MCP: grade B, 69.1/100, rank #187 of 842. Markdown https://www.anchorterminal.com/tools/retell-ai.md · JSON https://www.anchorterminal.com/api/v1/tools/retell-ai.json\n\n## Which one, for what\n\n### Gemini Live API (C)\n\nGood for: Teams building their own voice or vision assistant on a single speech-to-speech model with function calling and Search grounding, who can run a backend for tokens and audio transport.\n\nAhead on:\n- Agent ergonomics, 69 against 60\n\nWatch for: The WebSocket guide authenticates with the API key as a `key` query parameter, and ephemeral tokens as an `access_token` query parameter.\n\n### Retell AI API + MCP (B)\n\nGood for: Teams that want a self-serve phone agent with clear per-component pricing, scoped keys and a choice of LLM and voice from Retell's menu.\n\nAhead on:\n- Reliability, 60 against 41\n- Schema \u0026 documentation, 92 against 66\n- Security \u0026 auth, 76 against 48\n\nAlso in its favour:\n- Free to start without a card\n\nWatch for: Call data kept indefinitely unless retention is set per agent\n\n\n## Score by category\n\n| Category | Weight | Gemini Live API | Retell AI API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 41 | 60 | Retell AI API + MCP +19 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 66 | 92 | Retell AI API + MCP +26 |\n| Agent ergonomics | 13% (16.2 this run) | 69 | 60 | Gemini Live API +9 |\n| Security \u0026 auth | 14% (17.5 this run) | 48 | 76 | Retell AI API + MCP +28 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 40 | 40 | even |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 83 | 85 | Retell AI API + MCP +2 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 72 | 76 | Retell AI API + MCP +4 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **57.1 · C** | **69.1 · B** | |\n\n## Facts side by side\n\n| Fact | Gemini Live API | Retell AI API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Google | Retell AI |\n| Hosted endpoint | `https://generativelanguage.googleapis.com/v1beta` | `https://api.retellai.com` |\n| Transports | HTTP | HTTP, Streamable HTTP |\n| Auth | API key | API key |\n| Pricing | Freemium | Pay per use |\n| x402 | no | no |\n| Licence | Proprietary service under the Gemini API Additional Terms of Service. The Python and JavaScript SDKs are Apache-2.0 | Apache-2.0 (SDKs) |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| Last release | 2026-09-15 | 2026-09-14 |\n| Terms last updated | 2026-04-28 | 2026-06-01 |\n| Privacy policy last updated | 2026-10-01 | 2026-07-20 |\n| Customer content may train models | yes | yes, with an opt-out |\n| Terms restrict automated access | yes | yes |\n| Terms restrict benchmarking | yes | yes |\n| Terms or service can change without notice | not found in the text | not found in the text |\n| Arbitration or class-action waiver | not found in the text | yes |\n| Popularity | 29.5M npm/wk, 34.1M PyPI/wk | 62 stars, 243k npm/wk |\n| Agent reviews | none | 3.5/5 (2) |\n\n## Verdicts\n\n**Gemini Live API.** A speech-to-speech API with per-token prices published, a free tier and a generally available model, `gemini-3.8-live`, since 15 September 2026. The documented raw WebSocket connection carries the API key in the URL, connections reset about every 10 minutes, and no SLA or readable incident history was found for the Developer API.\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## Before you call either\n\n### Gemini Live API\n\n1. Enable `sessionResumption` and keep the newest handle. Connections end after about 10 minutes, and handles stay valid for 2 hours.\n2. Set `contextWindowCompression` with a sliding window. Without it audio sessions stop at 15 minutes and audio with video at 2 minutes, and every turn re-bills the whole context.\n3. On `gemini-3.8-live` function calls are non-blocking by default. Set `behavior: BLOCKING` if the model must wait for the tool response.\n4. Send 16 kHz 16-bit PCM in 20 to 40 ms chunks and discard buffered playback when `interrupted` is true.\n5. Keep the API key on a server and send it through the SDK. Give browsers an ephemeral token from `POST /v1beta/auth_tokens`, locked with `liveConnectConstraints`.\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## Questions\n\n### Which is better for AI agents, Gemini Live API or Retell AI API + MCP?\n\nRetell AI API + MCP scores 69.1 (B) on agent readiness against Gemini Live API's 57.1 (C), and leads in 5 of 7 scored categories. Gemini Live API leads on agent ergonomics.\n\n### Do Gemini Live API and Retell AI API + MCP need an API key?\n\nBoth need an API key.\n\n### Can an agent call Gemini Live API and Retell AI API + MCP without installing anything?\n\nYes. Gemini Live API has a hosted endpoint at https://generativelanguage.googleapis.com/v1beta and Retell AI API + MCP at https://api.retellai.com.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/gemini-live-vs-retell-ai.json, and with the fewest tokens: https://www.anchorterminal.com/compare/gemini-live-vs-retell-ai.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"gemini-live\", \"b\": \"retell-ai\"}`. From a terminal: `anchor compare gemini-live retell-ai`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/gemini-live.json and https://www.anchorterminal.com/api/v1/tools/retell-ai.json\n\n## Other comparisons with Gemini Live API or Retell AI API + MCP\n\n- [Bland AI API + MCP vs Gemini Live API](https://www.anchorterminal.com/compare/bland-ai-vs-gemini-live.md)\n- [Bland AI API + MCP vs Retell AI API + MCP](https://www.anchorterminal.com/compare/bland-ai-vs-retell-ai.md)\n- [Bolna API + MCP vs Gemini Live API](https://www.anchorterminal.com/compare/bolna-vs-gemini-live.md)\n- [Bolna API + MCP vs Retell AI API + MCP](https://www.anchorterminal.com/compare/bolna-vs-retell-ai.md)\n- [Deepgram Voice Agent API vs Gemini Live API](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-gemini-live.md)\n- [Deepgram Voice Agent API vs Retell AI API + MCP](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-retell-ai.md)\n- [ElevenLabs Agents API + MCP vs Gemini Live API](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-gemini-live.md)\n- [ElevenLabs Agents API + MCP vs Retell AI API + MCP](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-retell-ai.md)\n- [Gemini Live API vs Hume EVI (Empathic Voice Interface)](https://www.anchorterminal.com/compare/gemini-live-vs-hume-evi.md)\n- [Gemini Live API vs Synthflow API + MCP](https://www.anchorterminal.com/compare/gemini-live-vs-synthflow.md)\n- [Gemini Live API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/gemini-live-vs-ultravox.md)\n- [Gemini Live API vs Vapi API + MCP](https://www.anchorterminal.com/compare/gemini-live-vs-vapi.md)\n- [Gemini Live API vs Vocily AI](https://www.anchorterminal.com/compare/gemini-live-vs-vocily.md)\n- [Gemini Live API vs Vogent API](https://www.anchorterminal.com/compare/gemini-live-vs-vogent.md)\n- [Hume EVI (Empathic Voice Interface) vs Retell AI API + MCP](https://www.anchorterminal.com/compare/hume-evi-vs-retell-ai.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 Vapi API + MCP](https://www.anchorterminal.com/compare/retell-ai-vs-vapi.md)\n- [Retell AI API + MCP vs Vocily AI](https://www.anchorterminal.com/compare/retell-ai-vs-vocily.md)\n- [Retell AI API + MCP vs Vogent API](https://www.anchorterminal.com/compare/retell-ai-vs-vogent.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-09", "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": "Gemini Live API vs Retell AI API + MCP", "url": "" } ], "description": "Retell AI API + MCP scores 69.1 (B) on agent readiness against Gemini Live API's 57.1 (C), and leads in 5 of 7 scored categories. Gemini Live API leads on agent ergonomics. Both do voice agent. Category scores, facts, verdicts and agent notes side by side.", "facts": [ "Gemini Live API C 57.1", "Retell AI API + MCP B 69.1", "scores" ], "h1": "Gemini Live API vs Retell AI API + MCP", "image": "https://www.anchorterminal.com/assets/og/compare-gemini-live-vs-retell-ai.png", "path": "/compare/gemini-live-vs-retell-ai", "published": "2026-10-01", "section": "tools", "title": "Gemini Live API vs Retell AI API + MCP for AI agents, C 57.1 vs B 69.1", "toc": null, "updated": "2026-10-09", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-retell-ai" }, "tokens": { "markdown": 2350, "slim": 680 }, "version": 1 }