{ "data": { "a": { "slug": "openai-realtime", "name": "OpenAI Realtime API", "vendor": "OpenAI", "vendorUrl": "https://openai.com", "kind": "http-api", "category": "voice-agents", "summary": "OpenAI's Realtime API runs spoken conversations with speech-to-speech models such as `gpt-realtime-2.1`. Clients connect over WebRTC, WebSocket or SIP, and sessions support interruptions, function calling and remote MCP tools.", "url": "https://www.anchorterminal.com/tools/openai-realtime", "markdownUrl": "https://www.anchorterminal.com/tools/openai-realtime.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/openai-realtime.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/openai-realtime.json", "repo": "https://github.com/openai/openai-agents-js", "license": "Proprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MIT", "transports": [ "http" ], "remoteUrl": "https://api.openai.com/v1/realtime", "packages": [ { "registry": "npm", "name": "@openai/agents" }, { "registry": "npm", "name": "@openai/agents-realtime" } ], "auth": "api-key", "authNotes": "Self-serve API key from platform.openai.com, sent as a Bearer header on server WebSocket connections and call-control requests. For browsers and phones, a server calls `POST /v1/realtime/client_secrets` for a client secret (`ek_`) that lasts 10 seconds to 2 hours, 10 minutes by default, and can start several sessions until it expires. The browser WebSocket example passes the secret as a subprotocol. SIP calls are tied to a project by the project ID in the SIP address.", "pricing": "usage", "pricingNotes": "Per 1M tokens on `gpt-realtime-2.1`. Audio $32.00 in, $0.40 cached and $64.00 out, text $4.00 in and $24.00 out, image $5.00 in. `gpt-realtime-2.1-mini` is $10.00 and $20.00 for audio. Each response re-sends the whole conversation, and input transcription is billed separately. Usage tiers start at $5 of credit purchases. Whether the Free tier covers Realtime models was not established (https://developers.openai.com/api/docs/pricing.md, checked 2026-10-09).", "priceSummary": "Pay per use", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the Realtime guides, the pricing page or the OpenAPI file (checked 2026-10-09).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": null, "npmWeekly": null, "pypiWeekly": null, "asOf": "2026-10-09" }, "docsUrl": "https://developers.openai.com/api/docs/guides/realtime", "llmsTxt": "https://developers.openai.com/api/docs/llms.txt", "openapi": "https://github.com/openai/openai-openapi/blob/main/openapi.yaml", "capabilities": [ "voice.agent", "voice.speech-to-speech", "voice.tools", "voice.telephony" ], "tags": [ "hosted", "usage-priced", "closed-source", "speech-to-speech", "webrtc", "websocket", "sip", "streaming", "typescript", "python", "openapi", "llms-txt", "api-key", "function-calling", "mcp-client", "status-page" ], "lastRelease": "2026-07-28", "graded": true, "anchor": { "graded": true, "score": 63.3, "grade": "B", "agentReady": false, "rank": 400, "ranked": true, "rankOf": 950, "categoryRank": 7, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 76, "maintenance": 52, "payments": 20, "reliability": 67, "schema": 84, "security": 61, "transparency": 71 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "low", "date": "2026-10-09" }, "negative": 0, "verdict": "A generally available speech-to-speech API with WebRTC, WebSocket and SIP transports, a public OpenAPI file that types its events, and per-token prices. Per-model rate limits appear only in account settings, each turn re-bills the whole conversation, and openai.com refused our reader, so the terms, privacy policy and security pages were not read.", "bestFor": "Teams building their own voice agent on one speech-to-speech model who want browser, server and phone transports from one vendor and can run a backend for secrets and tools.", "strengths": [ "The OpenAPI 3.1 file in `openai/openai-openapi` covers nine Realtime paths and types 13 client events and 48 server events as schemas.", "Browser clients use client secrets that expire after 10 seconds to 2 hours, 10 minutes by default, so the API key stays on a server.", "Remote MCP tools accept an `allowed_tools` list, and `require_approval` defaults to `always` in the OpenAPI file.", "SIP calls connect at `sip.api.openai.com` with accept, reject, refer and hangup endpoints and a signed incoming-call webhook.", "The data controls page lists `/v1/realtime` with no training use, 30-day abuse logs, no stored application state and Zero Data Retention eligibility." ], "weaknesses": [ "openai.com answered 403 to our reader, so the service terms, privacy policy, sub-processor list and security pages were not read.", "Realtime rate limits are shown only in account settings. The public table gives numbers for GPT-6 model families only.", "Every response re-sends the whole conversation, so later turns cost more. Audio is $32 in and $64 out per 1M tokens on `gpt-realtime-2.1`.", "The status feed names Realtime among affected components in five incidents between 24 July and 6 October 2026, with durations not shown in the feed.", "Session settings attached to a client secret can be overridden by the client connection, per the client secret reference." ], "agentNotes": [ "Create a client secret on a server with `POST /v1/realtime/client_secrets` and give browsers only the `ek_` value. Never ship the API key.", "After a response with MCP calls finishes, send another `response.create`. The API does not create the follow-up response itself.", "Set `truncation` with a `retention_ratio` below 1 and `token_limits.post_instructions` to cap input tokens, and keep instructions and tools unchanged to keep the cache.", "On a WebSocket, stop playback on `input_audio_buffer.speech_started` and send `conversation.item.truncate` with `audio_end_ms`. WebRTC and SIP truncate on the server.", "Use `gpt-realtime-2.1` or `gpt-realtime-2.1-mini`. `gpt-realtime` and `gpt-realtime-mini` shut down on 20 January 2027." ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "low", "grade": "B", "methodology": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 63.3 } ], "editorialScores": { "ergonomics": 76, "maintenance": 52, "payments": 20, "reliability": 67, "schema": 84, "security": 61, "transparency": 58 }, "provenanceScore": 84 }, "connect": { "install": "npm install @openai/agents", "http": "curl -X POST https://api.openai.com/v1/realtime/client_secrets \\\n -H \"Authorization: Bearer $OPENAI_API_KEY\" -H \"Content-Type: application/json\" \\\n -d '{\"session\": {\"type\": \"realtime\", \"model\": \"gpt-realtime-2.1\"}}'" }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/openai-realtime" }, "sameCompany": [ "openai-api", "openai-embeddings", "openai-guardrails", "openai-moderation", "openai-image-api", "openai-sora", "openai-speech-to-text", "openai-agents-sdk", "openai-decisions-api", "openai-codex" ], "area": "voice", "unitPrices": [ { "item": "gpt-realtime-2.1 audio input", "unit": "1m-tokens", "usd": 32, "note": "$0.40 cached. 1 token per 100 ms of user audio, about $0.019 a minute before caching" }, { "item": "gpt-realtime-2.1 audio output", "unit": "1m-tokens", "usd": 64, "note": "1 token per 50 ms of assistant audio, about $0.077 a minute" }, { "item": "gpt-realtime-2.1 text input", "unit": "1m-tokens", "usd": 4, "note": "$0.40 cached" }, { "item": "gpt-realtime-2.1 text output", "unit": "1m-tokens", "usd": 24 }, { "item": "gpt-realtime-2.1-mini audio input", "unit": "1m-tokens", "usd": 10, "note": "$0.30 cached" }, { "item": "gpt-realtime-2.1-mini audio output", "unit": "1m-tokens", "usd": 20 } ], "provenance": { "legalEntity": "OpenAI", "domain": "openai.com", "domainRegistered": "2007-01-19", "endpointOnVendorDomain": true, "terms": "https://openai.com/policies/services-agreement/", "privacy": "https://openai.com/policies/privacy-policy/", "statusPage": "https://status.openai.com", "changelog": "https://developers.openai.com/api/docs/changelog", "securityTxt": "unknown", "checked": "2026-10-09", "notes": [ "The API, WebRTC and SIP endpoints are on api.openai.com and sip.api.openai.com. The docs are on developers.openai.com.", "RDAP for openai.com gives a registration date of 2007-01-19.", "The legal entity was not read. The SDK licence file says Copyright (c) 2025 OpenAI.", "robots.txt answered 200 on developers.openai.com and openai.com, allowing the pages read, and 404 on status.openai.com, which means no rules.", "openai.com answered our researcher with a bot check on 9 October 2026, so the terms and privacy policy were not read on that day. The links are the two documents OpenAI's other listings here carry. openai.com answers our policy reader with HTTP 403 as well, so neither document has been read and both are recorded as unreadable." ], "score": 84 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/openai-realtime.json", "live": { "slug": "openai-realtime", "probe": { "target": "https://api.openai.com/v1/realtime", "method": "get", "lastAt": "2026-10-10T03:53:36.846326361Z", "lastOk": true, "lastStatus": 405, "lastMs": 159, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 153, "p95ms24h": 201, "samples24h": 125, "samples30d": 125, "days": [ { "date": "2026-10-09", "probes": 85, "ok": 85 }, { "date": "2026-10-10", "probes": 40, "ok": 40 } ] }, "vendorStatus": { "page": "https://status.openai.com", "indicator": "minor", "summary": "Partial System Degradation", "checkedAt": "2026-10-10T03:58:36.458994883Z" }, "versions": [ { "registry": "github", "name": "openai/openai-agents-js", "version": "@openai/agents-extensions@0.20.0", "released": "2026-10-08", "seenAt": "2026-10-09T17:10:29.452928495Z" }, { "registry": "npm", "name": "@openai/agents", "version": "0.20.0", "seenAt": "2026-10-09T17:10:27.202909251Z" }, { "registry": "npm", "name": "@openai/agents-realtime", "version": "0.20.0", "seenAt": "2026-10-09T17:10:27.531105633Z" } ], "githubStars": 3903, "npmWeekly": 2125326, "pages": [ { "url": "https://developers.openai.com/api/docs/pricing.md", "kind": "pricing", "status": 200, "checkedAt": "2026-10-09T18:36:10.419663305Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "742c4d3c6b71" } ], "updatedAt": "2026-10-10T03:58:36.458994883Z" } }, "answer": "OpenAI Realtime API scores 63.3 (B) on agent readiness against Synthflow API + MCP's 51.1 (D), and leads in 5 of 7 scored categories. Synthflow API + MCP leads on maintenance \u0026 community.", "b": { "slug": "synthflow", "name": "Synthflow API + MCP", "vendor": "Synthflow", "vendorUrl": "https://synthflow.ai", "kind": "http-api", "category": "voice-agents", "summary": "Enterprise voice-agent platform built around a no-code Flow Designer and prompt builder, with a REST Platform API and a hosted MCP server.", "url": "https://www.anchorterminal.com/tools/synthflow", "markdownUrl": "https://www.anchorterminal.com/tools/synthflow.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/synthflow.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/synthflow.json", "repo": "https://github.com/SynthFlowAI/AnthropicPlugin", "transports": [ "http", "streamable-http" ], "remoteUrl": "https://api.synthflow.ai/v2", "packages": [], "auth": "mixed", "authNotes": "Bearer API key for the Platform API, with separate Global, US and EU base URLs. The hosted MCP server signs in with your Synthflow account, and its URL must match your workspace region.", "pricing": "paid", "pricingNotes": "Sales-led only. Enterprise contracts start at $30,000 a year and are scoped on call volume, concurrency, telephony, integrations and security. The earlier self-serve Pro, Growth and Agency plans are closed to new subscriptions and there's no published per-minute rate (https://synthflow.ai/pricing).", "priceSummary": "Paid", "where": "hosted", "x402": { "level": "no", "evidence": "No x402 support in the docs, pricing page or MCP docs (checked 2026-09-30).", "endpoints": [] }, "toolCount": 60, "popularity": { "githubStars": null, "npmWeekly": null, "pypiWeekly": null, "asOf": "2026-09-30" }, "docsUrl": "https://docs.synthflow.ai", "llmsTxt": "https://docs.synthflow.ai/llms.txt", "openapi": "https://docs.synthflow.ai/openapi.json", "capabilities": [ "voice.agent", "voice.pipeline", "voice.tools", "voice.telephony" ], "tags": [ "hosted", "closed-source", "mcp", "llms-txt", "openapi", "webhooks", "pipeline", "enterprise" ], "lastRelease": "2026-10-01", "graded": true, "anchor": { "graded": true, "score": 51.1, "grade": "D", "agentReady": false, "rank": 756, "ranked": true, "rankOf": 950, "categoryRank": 13, "methodology": "0.4", "run": "2026-10-01", "scores": { "ergonomics": 45, "maintenance": 68, "payments": 0, "reliability": 45, "schema": 87, "security": 51, "transparency": 66 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": 0, "verdict": "Changelog entries almost daily, ten between 7 September and 1 October 2026. Sales-led only, contracts from $30,000 a year, no free tier.", "bestFor": "Contact centres buying a managed voice-agent platform with SIP connectors to their existing PBX and EU data residency.", "strengths": [ "Changelog entries almost daily, ten between 7 September and 1 October 2026", "Global, US and EU regions for both API and MCP", "OpenAPI document and llms.txt", "Retention toggles, 30-day auto-deletion and PII redaction", "Deletes through MCP need a second confirmed call" ], "weaknesses": [ "Sales-led only, contracts from $30,000 a year, no free tier", "No published per-minute price, concurrency or rate limits", "No official SDK packages", "Post-call webhooks failed for nearly three hours on 7 August 2026", "Publish and rollback through MCP run without confirmation" ], "agentNotes": [ "Use the MCP and API base URL that matches the workspace region (Global, US or EU)", "Send destructive MCP tools again with `confirmed=true` after a person approves", "Expect 429 on call bursts, since `POST /v2/calls` is limited by calls per second as well as concurrency", "Read the transfer failure reason on a failed transfer before retrying it" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 2, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "D", "methodology": "0.4", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 51.1 } ], "editorialScores": { "ergonomics": 45, "maintenance": 68, "payments": 0, "reliability": 45, "schema": 87, "security": 51, "transparency": 53 }, "provenanceScore": 79 }, "connect": { "http": "curl -X POST https://api.synthflow.ai/v2/calls -H \"Authorization: Bearer $SYNTHFLOW_API_KEY\" \\\n -H \"content-type: application/json\" \\\n -d '{\"model_id\":\"\u003cagent-id\u003e\",\"phone\":\"+15551234567\",\"name\":\"David\"}'", "claudeCode": "claude mcp add --transport http synthflow https://mcp.synthflow.ai/mcp" }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/synthflow" }, "area": "voice", "provenance": { "legalEntity": "AgentFlow AI GmbH", "domain": "synthflow.ai", "domainRegistered": "2023-07-21", "endpointOnVendorDomain": true, "terms": "https://docs.synthflow.ai/terms-conditions", "privacy": "https://docs.synthflow.ai/privacy-policy", "statusPage": "https://status.synthflow.ai", "changelog": "https://docs.synthflow.ai/changelog", "securityTxt": "none", "checked": "2026-09-30", "score": 79 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/synthflow.json", "live": { "slug": "synthflow", "probe": { "target": "https://api.synthflow.ai/v2", "method": "get", "lastAt": "2026-10-10T03:53:45.953923301Z", "lastOk": true, "lastStatus": 404, "lastMs": 168, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 209, "p95ms24h": 426, "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.synthflow.ai", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-10T03:58:48.47852533Z" }, "githubStars": 0, "securityTxt": { "url": "https://synthflow.ai/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-09T15:40:36.936885564Z" }, "llmsTxt": { "url": "https://docs.synthflow.ai/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-09T14:02:52.647101669Z" }, "domain": { "domain": "synthflow.ai", "registered": "2023-07-21", "source": "https://rdap.identitydigital.services/rdap/domain/synthflow.ai", "checkedAt": "2026-10-04T13:05:22.70407658Z" }, "pages": [ { "url": "https://docs.synthflow.ai/changelog", "kind": "changelog", "status": 200, "checkedAt": "2026-10-09T18:38:28.921312202Z", "changedAt": "2026-10-09T18:38:28.921312202Z", "fingerprint": "51618d8888bf" }, { "url": "https://synthflow.ai/pricing", "kind": "pricing", "status": 304, "checkedAt": "2026-10-09T18:46:27.271958326Z", "changedAt": "2026-10-06T16:12:57.389510458Z", "fingerprint": "51552cf587c5" }, { "url": "https://docs.synthflow.ai/privacy-policy", "kind": "privacy", "status": 304, "checkedAt": "2026-10-09T18:38:31.326898135Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "efaf26369f90" }, { "url": "https://docs.synthflow.ai/terms-conditions", "kind": "terms", "status": 304, "checkedAt": "2026-10-09T18:38:33.657968355Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "3ed62f6822c3" } ], "updatedAt": "2026-10-10T03:58:48.47852533Z" } }, "facts": [ { "a": "HTTP API", "b": "HTTP API", "name": "Kind" }, { "a": "OpenAI", "b": "Synthflow", "name": "Vendor" }, { "a": "https://api.openai.com/v1/realtime", "b": "https://api.synthflow.ai/v2", "name": "Hosted endpoint" }, { "a": "HTTP", "b": "HTTP, Streamable HTTP", "name": "Transports" }, { "a": "API key", "b": "OAuth or key", "name": "Auth" }, { "a": "Pay per use", "b": "Paid", "name": "Pricing" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "Proprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MIT", "b": "none", "name": "Licence" }, { "a": "none", "b": "60", "name": "Tools exposed" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "yes", "name": "llms.txt" }, { "a": "2026-07-28", "b": "2026-10-01", "name": "Last release" }, { "a": "couldn't be read", "b": "2026-05-13", "name": "Terms last updated" }, { "a": "couldn't be read", "b": "no date given", "name": "Privacy policy last updated" }, { "a": "couldn't be read", "b": "not found in the text", "name": "Customer content may train models" }, { "a": "couldn't be read", "b": "not found in the text", "name": "Terms restrict automated access" }, { "a": "couldn't be read", "b": "not found in the text", "name": "Terms restrict benchmarking" }, { "a": "couldn't be read", "b": "not found in the text", "name": "Terms or service can change without notice" }, { "a": "couldn't be read", "b": "not found in the text", "name": "Arbitration or class-action waiver" }, { "a": "none", "b": "2/5 (2)", "name": "Agent reviews" } ], "faq": [ { "answer": "OpenAI Realtime API scores 63.3 (B) on agent readiness against Synthflow API + MCP's 51.1 (D), and leads in 5 of 7 scored categories. Synthflow API + MCP leads on maintenance \u0026 community.", "question": "Which is better for AI agents, OpenAI Realtime API or Synthflow API + MCP?" }, { "answer": "OpenAI Realtime API needs an API key. Synthflow API + MCP takes an API key or an OAuth sign-in.", "question": "Do OpenAI Realtime API and Synthflow API + MCP need an API key?" }, { "answer": "Yes. OpenAI Realtime API has a hosted endpoint at https://api.openai.com/v1/realtime and Synthflow API + MCP at https://api.synthflow.ai/v2.", "question": "Can an agent call OpenAI Realtime API and Synthflow API + MCP without installing anything?" } ], "goodFor": [ { "aheadOn": [ "Reliability, 67 against 45", "Agent ergonomics, 76 against 45", "Security \u0026 auth, 61 against 51", "Payments \u0026 pricing, 20 against 0", "Transparency \u0026 trust, 71 against 66" ], "also": null, "goodFor": "Teams building their own voice agent on one speech-to-speech model who want browser, server and phone transports from one vendor and can run a backend for secrets and tools.", "slug": "openai-realtime", "watchFor": "openai.com answered 403 to our reader, so the service terms, privacy policy, sub-processor list and security pages were not read." }, { "aheadOn": [ "Maintenance \u0026 community, 68 against 52" ], "also": null, "goodFor": "Contact centres buying a managed voice-agent platform with SIP connectors to their existing PBX and EU data residency.", "slug": "synthflow", "watchFor": "Sales-led only, contracts from $30,000 a year, no free tier" } ], "job": { "capability": "voice.agent", "name": "Voice agents" }, "others": [ { "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-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/bland-ai-vs-openai-realtime.json", "title": "Bland AI API + MCP vs OpenAI Realtime API", "url": "https://www.anchorterminal.com/compare/bland-ai-vs-openai-realtime" }, { "json": "https://www.anchorterminal.com/compare/bland-ai-vs-synthflow.json", "title": "Bland AI API + MCP vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/bland-ai-vs-synthflow" }, { "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-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/deepgram-voice-agent-vs-openai-realtime.json", "title": "Deepgram Voice Agent API vs OpenAI Realtime API", "url": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-openai-realtime" }, { "json": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-synthflow.json", "title": "Deepgram Voice Agent API vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-synthflow" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime.json", "title": "ElevenLabs Agents API + MCP vs OpenAI Realtime API", "url": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-synthflow.json", "title": "ElevenLabs Agents API + MCP vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-synthflow" }, { "json": "https://www.anchorterminal.com/compare/gemini-live-vs-openai-realtime.json", "title": "Gemini Live API vs OpenAI Realtime API", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-openai-realtime" }, { "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/hume-evi-vs-openai-realtime.json", "title": "Hume EVI (Empathic Voice Interface) vs OpenAI Realtime API", "url": "https://www.anchorterminal.com/compare/hume-evi-vs-openai-realtime" }, { "json": "https://www.anchorterminal.com/compare/hume-evi-vs-synthflow.json", "title": "Hume EVI (Empathic Voice Interface) vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/hume-evi-vs-synthflow" }, { "json": "https://www.anchorterminal.com/compare/openai-realtime-vs-retell-ai.json", "title": "OpenAI Realtime API vs Retell AI API + MCP", "url": "https://www.anchorterminal.com/compare/openai-realtime-vs-retell-ai" }, { "json": "https://www.anchorterminal.com/compare/openai-realtime-vs-ultravox.json", "title": "OpenAI Realtime API vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/openai-realtime-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/openai-realtime-vs-vapi.json", "title": "OpenAI Realtime API vs Vapi API + MCP", "url": "https://www.anchorterminal.com/compare/openai-realtime-vs-vapi" }, { "json": "https://www.anchorterminal.com/compare/openai-realtime-vs-vocily.json", "title": "OpenAI Realtime API vs Vocily AI", "url": "https://www.anchorterminal.com/compare/openai-realtime-vs-vocily" }, { "json": "https://www.anchorterminal.com/compare/openai-realtime-vs-vogent.json", "title": "OpenAI Realtime API vs Vogent API", "url": "https://www.anchorterminal.com/compare/openai-realtime-vs-vogent" }, { "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/synthflow-vs-ultravox.json", "title": "Synthflow API + MCP vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/synthflow-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/synthflow-vs-vapi.json", "title": "Synthflow API + MCP vs Vapi API + MCP", "url": "https://www.anchorterminal.com/compare/synthflow-vs-vapi" }, { "json": "https://www.anchorterminal.com/compare/synthflow-vs-vocily.json", "title": "Synthflow API + MCP vs Vocily AI", "url": "https://www.anchorterminal.com/compare/synthflow-vs-vocily" }, { "json": "https://www.anchorterminal.com/compare/synthflow-vs-vogent.json", "title": "Synthflow API + MCP vs Vogent API", "url": "https://www.anchorterminal.com/compare/synthflow-vs-vogent" } ], "scores": [ { "by": 22, "edge": "openai-realtime", "key": "reliability", "name": "Reliability", "openai-realtime": 67, "synthflow": 45, "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 3, "edge": "synthflow", "key": "schema", "name": "Schema \u0026 documentation", "openai-realtime": 84, "synthflow": 87, "weight": 13 }, { "by": 31, "edge": "openai-realtime", "key": "ergonomics", "name": "Agent ergonomics", "openai-realtime": 76, "synthflow": 45, "weight": 13 }, { "by": 10, "edge": "openai-realtime", "key": "security", "name": "Security \u0026 auth", "openai-realtime": 61, "synthflow": 51, "weight": 14 }, { "by": 20, "edge": "openai-realtime", "key": "payments", "name": "Payments \u0026 pricing", "openai-realtime": 20, "synthflow": 0, "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 16, "edge": "synthflow", "key": "maintenance", "name": "Maintenance \u0026 community", "openai-realtime": 52, "synthflow": 68, "weight": 7 }, { "by": 5, "edge": "openai-realtime", "key": "transparency", "name": "Transparency \u0026 trust", "openai-realtime": 71, "synthflow": 66, "weight": 7 } ], "summary": "OpenAI Realtime API scores 63.3 (B) on agent readiness against Synthflow API + MCP's 51.1 (D), and leads in 5 of 7 scored categories. Synthflow API + MCP leads on maintenance \u0026 community. Both do voice agents.", "verdicts": { "openai-realtime": "A generally available speech-to-speech API with WebRTC, WebSocket and SIP transports, a public OpenAPI file that types its events, and per-token prices. Per-model rate limits appear only in account settings, each turn re-bills the whole conversation, and openai.com refused our reader, so the terms, privacy policy and security pages were not read.", "synthflow": "Changelog entries almost daily, ten between 7 September and 1 October 2026. Sales-led only, contracts from $30,000 a year, no free tier." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow", "json": "https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow.md", "slim": "https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow.min.md" }, "markdown": "OpenAI Realtime API scores 63.3 (B) on agent readiness against Synthflow API + MCP's 51.1 (D), and leads in 5 of 7 scored categories. Synthflow API + MCP leads on maintenance \u0026 community. Both do voice agents.\n\n- OpenAI Realtime API: grade B, 63.3/100, rank #400 of 950. Markdown https://www.anchorterminal.com/tools/openai-realtime.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-realtime.json\n- Synthflow API + MCP: grade D, 51.1/100, rank #756 of 950. Markdown https://www.anchorterminal.com/tools/synthflow.md · JSON https://www.anchorterminal.com/api/v1/tools/synthflow.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### OpenAI Realtime API (B)\n\nGood for: Teams building their own voice agent on one speech-to-speech model who want browser, server and phone transports from one vendor and can run a backend for secrets and tools.\n\nAhead on:\n- Reliability, 67 against 45\n- Agent ergonomics, 76 against 45\n- Security \u0026 auth, 61 against 51\n- Payments \u0026 pricing, 20 against 0\n- Transparency \u0026 trust, 71 against 66\n\nWatch for: openai.com answered 403 to our reader, so the service terms, privacy policy, sub-processor list and security pages were not read.\n\n### Synthflow API + MCP (D)\n\nGood for: Contact centres buying a managed voice-agent platform with SIP connectors to their existing PBX and EU data residency.\n\nAhead on:\n- Maintenance \u0026 community, 68 against 52\n\nWatch for: Sales-led only, contracts from $30,000 a year, no free tier\n\n\n## Score by category\n\n| Category | Weight | OpenAI Realtime API | Synthflow API + MCP | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 67 | 45 | OpenAI Realtime API +22 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 84 | 87 | Synthflow API + MCP +3 |\n| Agent ergonomics | 13% (16.2 this run) | 76 | 45 | OpenAI Realtime API +31 |\n| Security \u0026 auth | 14% (17.5 this run) | 61 | 51 | OpenAI Realtime API +10 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 20 | 0 | OpenAI Realtime API +20 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 52 | 68 | Synthflow API + MCP +16 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 71 | 66 | OpenAI Realtime API +5 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **63.3 · B** | **51.1 · D** | |\n\n## Facts side by side\n\n| Fact | OpenAI Realtime API | Synthflow API + MCP |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | OpenAI | Synthflow |\n| Hosted endpoint | `https://api.openai.com/v1/realtime` | `https://api.synthflow.ai/v2` |\n| Transports | HTTP | HTTP, Streamable HTTP |\n| Auth | API key | OAuth or key |\n| Pricing | Pay per use | Paid |\n| x402 | no | no |\n| Licence | Proprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MIT | none |\n| Tools exposed | none | 60 |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| Last release | 2026-07-28 | 2026-10-01 |\n| Terms last updated | couldn't be read | 2026-05-13 |\n| Privacy policy last updated | couldn't be read | no date given |\n| Customer content may train models | couldn't be read | not found in the text |\n| Terms restrict automated access | couldn't be read | not found in the text |\n| Terms restrict benchmarking | couldn't be read | not found in the text |\n| Terms or service can change without notice | couldn't be read | not found in the text |\n| Arbitration or class-action waiver | couldn't be read | not found in the text |\n| Agent reviews | none | 2/5 (2) |\n\n## Verdicts\n\n**OpenAI Realtime API.** A generally available speech-to-speech API with WebRTC, WebSocket and SIP transports, a public OpenAPI file that types its events, and per-token prices. Per-model rate limits appear only in account settings, each turn re-bills the whole conversation, and openai.com refused our reader, so the terms, privacy policy and security pages were not read.\n\n**Synthflow API + MCP.** Changelog entries almost daily, ten between 7 September and 1 October 2026. Sales-led only, contracts from $30,000 a year, no free tier.\n\n## Before you call either\n\n### OpenAI Realtime API\n\n1. Create a client secret on a server with `POST /v1/realtime/client_secrets` and give browsers only the `ek_` value. Never ship the API key.\n2. After a response with MCP calls finishes, send another `response.create`. The API does not create the follow-up response itself.\n3. Set `truncation` with a `retention_ratio` below 1 and `token_limits.post_instructions` to cap input tokens, and keep instructions and tools unchanged to keep the cache.\n4. On a WebSocket, stop playback on `input_audio_buffer.speech_started` and send `conversation.item.truncate` with `audio_end_ms`. WebRTC and SIP truncate on the server.\n5. Use `gpt-realtime-2.1` or `gpt-realtime-2.1-mini`. `gpt-realtime` and `gpt-realtime-mini` shut down on 20 January 2027.\n\n### Synthflow API + MCP\n\n1. Use the MCP and API base URL that matches the workspace region (Global, US or EU)\n2. Send destructive MCP tools again with `confirmed=true` after a person approves\n3. Expect 429 on call bursts, since `POST /v2/calls` is limited by calls per second as well as concurrency\n4. Read the transfer failure reason on a failed transfer before retrying it\n\n## Questions\n\n### Which is better for AI agents, OpenAI Realtime API or Synthflow API + MCP?\n\nOpenAI Realtime API scores 63.3 (B) on agent readiness against Synthflow API + MCP's 51.1 (D), and leads in 5 of 7 scored categories. Synthflow API + MCP leads on maintenance \u0026 community.\n\n### Do OpenAI Realtime API and Synthflow API + MCP need an API key?\n\nOpenAI Realtime API needs an API key. Synthflow API + MCP takes an API key or an OAuth sign-in.\n\n### Can an agent call OpenAI Realtime API and Synthflow API + MCP without installing anything?\n\nYes. OpenAI Realtime API has a hosted endpoint at https://api.openai.com/v1/realtime and Synthflow API + MCP at https://api.synthflow.ai/v2.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow.json, and with the fewest tokens: https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"openai-realtime\", \"b\": \"synthflow\"}`. From a terminal: `anchor compare openai-realtime synthflow`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/openai-realtime.json and https://www.anchorterminal.com/api/v1/tools/synthflow.json\n\n## Other comparisons with OpenAI Realtime API or Synthflow API + MCP\n\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 Synthflow API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-synthflow.md)\n- [Bland AI API + MCP vs OpenAI Realtime API](https://www.anchorterminal.com/compare/bland-ai-vs-openai-realtime.md)\n- [Bland AI API + MCP vs Synthflow API + MCP](https://www.anchorterminal.com/compare/bland-ai-vs-synthflow.md)\n- [Bolna API + MCP vs OpenAI Realtime API](https://www.anchorterminal.com/compare/bolna-vs-openai-realtime.md)\n- [Bolna API + MCP vs Synthflow API + MCP](https://www.anchorterminal.com/compare/bolna-vs-synthflow.md)\n- [Deepgram Voice Agent API vs OpenAI Realtime API](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-openai-realtime.md)\n- [Deepgram Voice Agent API vs Synthflow API + MCP](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-synthflow.md)\n- [ElevenLabs Agents API + MCP vs OpenAI Realtime API](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-openai-realtime.md)\n- [ElevenLabs Agents API + MCP vs Synthflow API + MCP](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-synthflow.md)\n- [Gemini Live API vs OpenAI Realtime API](https://www.anchorterminal.com/compare/gemini-live-vs-openai-realtime.md)\n- [Gemini Live API vs Synthflow API + MCP](https://www.anchorterminal.com/compare/gemini-live-vs-synthflow.md)\n- [Hume EVI (Empathic Voice Interface) vs OpenAI Realtime API](https://www.anchorterminal.com/compare/hume-evi-vs-openai-realtime.md)\n- [Hume EVI (Empathic Voice Interface) vs Synthflow API + MCP](https://www.anchorterminal.com/compare/hume-evi-vs-synthflow.md)\n- [OpenAI Realtime API vs Retell AI API + MCP](https://www.anchorterminal.com/compare/openai-realtime-vs-retell-ai.md)\n- [OpenAI Realtime API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/openai-realtime-vs-ultravox.md)\n- [OpenAI Realtime API vs Vapi API + MCP](https://www.anchorterminal.com/compare/openai-realtime-vs-vapi.md)\n- [OpenAI Realtime API vs Vocily AI](https://www.anchorterminal.com/compare/openai-realtime-vs-vocily.md)\n- [OpenAI Realtime API vs Vogent API](https://www.anchorterminal.com/compare/openai-realtime-vs-vogent.md)\n- [Retell AI API + MCP vs Synthflow API + MCP](https://www.anchorterminal.com/compare/retell-ai-vs-synthflow.md)\n- [Synthflow API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/synthflow-vs-ultravox.md)\n- [Synthflow API + MCP vs Vapi API + MCP](https://www.anchorterminal.com/compare/synthflow-vs-vapi.md)\n- [Synthflow API + MCP vs Vocily AI](https://www.anchorterminal.com/compare/synthflow-vs-vocily.md)\n- [Synthflow API + MCP vs Vogent API](https://www.anchorterminal.com/compare/synthflow-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": "OpenAI Realtime API vs Synthflow API + MCP", "url": "" } ], "description": "OpenAI Realtime scores 63.3 (B) to Synthflow's 51.1 (D) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.", "facts": [ "OpenAI Realtime API B 63.3", "Synthflow API + MCP D 51.1", "scores" ], "h1": "OpenAI Realtime API vs Synthflow API + MCP", "image": "https://www.anchorterminal.com/assets/og/compare-openai-realtime-vs-synthflow.png", "path": "/compare/openai-realtime-vs-synthflow", "published": "2026-10-01", "section": "tools", "title": "OpenAI Realtime vs Synthflow for AI agents in 2026: scores and prices", "toc": null, "updated": "2026-10-09", "url": "https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow" }, "tokens": { "markdown": 2600, "slim": 730 }, "version": 1 }