{ "data": { "a": { "slug": "rime-prism", "name": "Rime Prism", "vendor": "Rime Labs", "vendorUrl": "https://www.rime.ai/prism", "kind": "http-api", "category": "voice-agents", "summary": "Prism is Rime's speech-to-speech model for voice agents. It takes caller audio over one WebSocket, decides when the caller has finished, calls the developer's tools and replies in speech with matching text, in English.", "url": "https://www.anchorterminal.com/tools/rime-prism", "markdownUrl": "https://www.anchorterminal.com/tools/rime-prism.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/rime-prism.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/rime-prism.json", "license": "Proprietary hosted service under Rime's terms. The Rime SDK used to call it (github.com/rimelabs/rime-sdk) is MIT.", "transports": [ "websocket" ], "remoteUrl": "wss://prism.api.rime.ai/v1/realtime", "packages": [ { "registry": "pypi", "name": "rimelabs-sdk" }, { "registry": "npm", "name": "@rimelabs/sdk" }, { "registry": "go", "name": "github.com/rimelabs/rime-sdk/go" }, { "registry": "cargo", "name": "rimelabs-sdk" } ], "auth": "api-key", "authNotes": "Rime API key from the dashboard, sent as `Authorization: Bearer` on the WebSocket upgrade from a backend. Prism reads no query parameters, so the key can't go in the URL, and it has no ephemeral tokens for browsers or phones. The same key covers Rime's text-to-speech and speech-to-text. No scoped or read-only keys were found in the docs.", "pricing": "freemium", "pricingNotes": "$0.08 a minute of call audio on Flex (pay as you go, card billed monthly) and $0.064 on Scale ($100 a month of credit, 20% off). Every account gets $50 of usage a month across Rime's models, Prism included, with no card. Fine-tuning, custom voices, VPC or on-prem deployment, SLAs and a BAA are Enterprise items with custom pricing (https://www.rime.ai/pricing, checked 2026-10-28).", "priceSummary": "Freemium", "where": "hosted", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the Prism docs, the API reference or the pricing page, checked 2026-10-28. Paid plans bill a card monthly.", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": null, "npmWeekly": null, "pypiWeekly": null, "asOf": "2026-10-28" }, "docsUrl": "https://docs.rime.ai/docs/prism/overview", "llmsTxt": "https://docs.rime.ai/llms.txt", "capabilities": [ "voice.speech-to-speech", "voice.agent", "voice.tools" ], "tags": [ "hosted", "freemium", "no-card", "free-tier", "closed-source", "speech-to-speech", "websocket", "streaming", "function-calling", "llms-txt", "python", "typescript", "go", "rust", "status-page", "soc2", "hipaa", "enterprise" ], "lastRelease": "2026-10-28", "graded": true, "anchor": { "graded": true, "score": 57.9, "grade": "C", "agentReady": false, "rank": 686, "ranked": true, "rankOf": 1222, "categoryRank": 14, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 73, "maintenance": 65, "payments": 40, "reliability": 41, "schema": 69, "security": 56, "transparency": 70 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-28" }, "negative": 0, "verdict": "Prism's WebSocket API is well documented for a launch-day product, with typed events, 41 error codes that say what to do and a published per-minute price with free monthly usage. It has no Prism component or history on Rime's status page, no published concurrency limit, alpha SDKs, English only, and no data-handling statement that covers caller audio.", "bestFor": "English voice agents on Rime's cloud that want one speech-to-speech model with their own tools, and teams moving an OpenAI Realtime beta client who can bridge phone audio themselves.", "strengths": [ "Errors page lists 41 codes, each with scope, the field at fault, a correlation ID and what to do", "$0.08 a minute on Flex, with $50 of free usage a month and no card", "Uses OpenAI Realtime beta event names, with a migration guide for WebSocket, LiveKit, Pipecat and OpenAI SDK clients", "Key only in the upgrade header, and Prism reads no query parameters", "Context truncation is configurable and each reply reports what was left out and its token usage" ], "weaknesses": [ "Rime's status page had no Prism component on launch day, and there is no incident history for it", "No concurrency limit per account or key was found, and a full server refuses with 503", "All four SDKs are 0.1.0 alpha releases that may change their API", "English only, four voices, 16 kHz PCM16 in, with no mu-law, so phone calls need a bridge", "Privacy and security pages describe text in, audio out, and say nothing specific about caller audio" ], "agentNotes": [ "Connect from a backend with `Authorization: Bearer`, since Prism has no browser tokens and reads no query parameters.", "Send `session.update` before any audio, or every append fails with `session_not_initialized`.", "Keep streaming audio, silence included, while Prism speaks, because it finds turn ends and interruptions from that audio.", "Ask for the continuation after each tool result, since Prism doesn't resume on its own, and never rerun a call with an unknown outcome.", "Pin the exact SDK version, because the SDKs are alpha and a new release can change the API." ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 57.9 } ], "editorialScores": { "ergonomics": 73, "maintenance": 65, "payments": 40, "reliability": 41, "schema": 69, "security": 56, "transparency": 58 }, "provenanceScore": 81, "checked": { "categories": { "ergonomics": "2026-10-28", "maintenance": "2026-10-28", "payments": "2026-10-28", "reliability": "2026-10-28", "schema": "2026-10-28", "security": "2026-10-28", "transparency": "2026-10-28" }, "last": "2026-10-28", "oldest": "2026-10-28", "stale": false, "staleAfterDays": 90 } }, "connect": { "install": "uv add \"rimelabs-sdk==0.1.0a25\"" }, "letme": { "capability": "https://letme.dev/voice.speech-to-speech", "tool": "https://letme.dev/rime-prism" }, "sameCompany": [ "rime-tts" ], "area": "voice", "unitPrices": [ { "item": "Prism, Flex", "unit": "call-minute", "usd": 0.08, "note": "Metered by the minute of call audio, pay as you go. Pricing page, checked 28 October 2026" }, { "item": "Prism, Scale", "unit": "call-minute", "usd": 0.064, "note": "20% off Flex for $100 a month of credit, which rolls over up to $200. Pricing page, checked 28 October 2026" } ], "provenance": { "legalEntity": "Rime Labs, Inc.", "domain": "rime.ai", "domainRegistered": "2020-03-12", "endpointOnVendorDomain": true, "terms": "https://www.rime.ai/terms", "privacy": "https://www.rime.ai/privacy", "statusPage": "https://www.rimestat.us", "changelog": "https://docs.rime.ai/docs/changelog", "securityTxt": "none", "checked": "2026-10-28", "notes": [ "The terms name Rime Labs, Inc., the same entity as the rime-tts listing. The domain registration date stands per that listing's check of 30 September 2026 and wasn't re-read.", "status.rime.ai redirects to www.rimestat.us, an incident.io page with Text-to-speech API and Platform API components and data since 30 August 2026. It had no Prism component on 28 October 2026.", "www.rime.ai/.well-known/security.txt answered 404. The security page links a vulnerability disclosure policy.", "The Prism endpoint is on prism.api.rime.ai, under the vendor's own domain." ], "score": 81 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/rime-prism.json", "live": { "slug": "rime-prism", "probe": { "target": "wss://prism.api.rime.ai/v1/realtime", "method": "get", "lastAt": "2026-10-29T20:41:25.616992818Z", "lastOk": false, "lastStatus": 0, "lastMs": 0, "lastNote": "unsupported protocol scheme \"wss\"", "authRequired": false, "uptime24h": 0, "uptime30d": 0, "p50ms24h": 0, "p95ms24h": 0, "samples24h": 36, "samples30d": 36, "days": [ { "date": "2026-10-29", "probes": 36, "ok": 0 } ], "outages": [ { "start": "2026-10-29T17:19:57.075096127Z", "end": "0001-01-01T00:00:00Z", "note": "unsupported protocol scheme \"wss\"" } ] }, "vendorStatus": { "page": "https://www.rimestat.us", "indicator": "none", "summary": "All Systems Operational", "checkedAt": "2026-10-29T20:31:37.377251634Z" }, "updatedAt": "2026-10-29T20:41:25.616992818Z" } }, "answer": "Ultravox Realtime API and Rime Prism score within a point of each other on agent readiness, 58.6 (C) and 57.9 (C). Rime Prism leads on security \u0026 auth and maintenance \u0026 community.", "b": { "slug": "ultravox", "name": "Ultravox Realtime API", "vendor": "Ultravox (Fixie.ai)", "vendorUrl": "https://www.ultravox.ai", "kind": "http-api", "category": "voice-agents", "summary": "Hosted voice agents on Ultravox, an open-weight model that takes speech directly with no speech-to-text step and answers through a TTS voice.", "url": "https://www.anchorterminal.com/tools/ultravox", "markdownUrl": "https://www.anchorterminal.com/tools/ultravox.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/ultravox.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/ultravox.json", "repo": "https://github.com/fixie-ai/ultravox", "license": "MIT (model code)", "transports": [ "http" ], "remoteUrl": "https://api.ultravox.ai/api", "packages": [ { "registry": "npm", "name": "ultravox-client" }, { "registry": "pypi", "name": "ultravox-client" } ], "auth": "api-key", "authNotes": "`X-API-Key` header on the REST API. Clients join a call with the `joinUrl` returned when it's created, so the key stays on your server.", "pricing": "usage", "pricingNotes": "Pay as you go at $0.05 a minute after 30 free minutes, capped at 5 concurrent calls. Pro is $100 a month (annual rate) at the same $0.05 a minute with no hard concurrency cap, the outbound scheduler, 5 custom voices and 20 RAG corpora. SIP costs 0.5 cents a minute (0.48 on Pro). Threads are $2 per 1M input tokens and $15 per 1M output. Enterprise is custom. Telephony from Twilio or other carriers is billed by them (https://www.ultravox.ai/pricing).", "priceSummary": "$100 / 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": 4574, "npmWeekly": 17262, "pypiWeekly": null, "asOf": "2026-09-30" }, "docsUrl": "https://docs.ultravox.ai", "llmsTxt": "https://docs.ultravox.ai/llms.txt", "openapi": "https://api.ultravox.ai/api/schema/", "capabilities": [ "voice.agent", "voice.speech-to-speech", "voice.tools", "voice.telephony" ], "tags": [ "hosted", "open-weights", "no-card", "llms-txt", "openapi", "typescript", "python", "webhooks", "streaming", "speech-to-speech" ], "lastRelease": "2026-07-18", "graded": true, "anchor": { "graded": true, "score": 58.6, "grade": "C", "agentReady": false, "rank": 661, "ranked": true, "rankOf": 1222, "categoryRank": 13, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 69, "maintenance": 43, "payments": 40, "reliability": 52, "schema": 84, "security": 46, "transparency": 74 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": 0, "verdict": "Flat $0.05 a minute including model and built-in voices. No MCP server.", "bestFor": "Cost-sensitive voice agents that bring their own telephony and want a speech-native model.", "strengths": [ "Flat $0.05 a minute including model and built-in voices", "Speech-native model with no separate STT stage, v0.7 weights public under MIT", "429 and 503 responses with Retry-After and backoff guidance", "Deprecation guide with a minimum 30-day window", "Privacy policy says voice data isn't used for training" ], "weaknesses": [ "No MCP server", "News page, deprecation guide and Python client last updated in December 2025", "Plain API keys with no scopes", "Pay as you go caps at 5 concurrent calls", "No subprocessor list or stated certification" ], "agentNotes": [ "Honour `Retry-After` on 429 and 503 when creating calls", "Pin the model string (`ultravox-v0.7` or `ultravox-v0.6`) rather than relying on the default", "Hand clients the `joinUrl`, never the API key", "Delete calls through the API when you need data removed, there's no retention setting", "Use call stages for multi-step flows instead of one long prompt" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 3, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 58.6 } ], "editorialScores": { "ergonomics": 69, "maintenance": 43, "payments": 40, "reliability": 52, "schema": 84, "security": 46, "transparency": 67 }, "provenanceScore": 80, "checked": { "categories": { "ergonomics": "2026-10-01", "maintenance": "2026-10-01", "payments": "2026-10-01", "reliability": "2026-10-01", "schema": "2026-10-01", "security": "2026-10-01", "transparency": "2026-10-01" }, "last": "2026-10-01", "lastMoved": "2026-10-29", "oldest": "2026-10-01", "stale": false, "staleAfterDays": 90 } }, "connect": { "http": "curl -X POST https://api.ultravox.ai/api/calls -H \"X-API-Key: $ULTRAVOX_API_KEY\" \\\n -H \"content-type: application/json\" \\\n -d '{\"systemPrompt\":\"You are a friendly receptionist.\",\"voice\":\"Mark\"}'" }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/ultravox" }, "sameCompany": [ "ultravox-voice-cloning" ], "area": "voice", "unitPrices": [ { "item": "Ultravox Realtime", "unit": "call-minute", "usd": 0.05, "note": "model and built-in voices, telephony carrier costs extra" }, { "item": "SIP", "unit": "call-minute", "usd": 0.005, "note": "0.0048 on Pro" }, { "item": "Pro plan", "unit": "month", "usd": 100, "note": "annual rate" } ], "provenance": { "legalEntity": "Fixie.ai Inc.", "domain": "ultravox.ai", "domainRegistered": "2023-10-05", "endpointOnVendorDomain": true, "terms": "https://www.ultravox.ai/terms", "privacy": "https://www.ultravox.ai/privacy", "statusPage": "https://status.ultravox.ai", "changelog": "https://docs.ultravox.ai/changelog/news", "securityTxt": "none", "checked": "2026-09-30", "score": 80 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/ultravox.json", "live": { "slug": "ultravox", "probe": { "target": "https://api.ultravox.ai/api", "method": "get", "lastAt": "2026-10-29T20:41:33.220034195Z", "lastOk": true, "lastStatus": 404, "lastMs": 147, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 145, "p95ms24h": 238, "samples24h": 249, "samples30d": 7416, "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": 247, "ok": 247 }, { "date": "2026-10-11", "probes": 247, "ok": 247 }, { "date": "2026-10-12", "probes": 247, "ok": 247 }, { "date": "2026-10-13", "probes": 248, "ok": 248 }, { "date": "2026-10-14", "probes": 249, "ok": 249 }, { "date": "2026-10-15", "probes": 253, "ok": 253 }, { "date": "2026-10-16", "probes": 252, "ok": 252 }, { "date": "2026-10-17", "probes": 253, "ok": 253 }, { "date": "2026-10-18", "probes": 256, "ok": 256 }, { "date": "2026-10-19", "probes": 255, "ok": 255 }, { "date": "2026-10-20", "probes": 252, "ok": 252 }, { "date": "2026-10-21", "probes": 253, "ok": 253 }, { "date": "2026-10-22", "probes": 253, "ok": 253 }, { "date": "2026-10-23", "probes": 248, "ok": 248 }, { "date": "2026-10-24", "probes": 251, "ok": 251 }, { "date": "2026-10-25", "probes": 250, "ok": 250 }, { "date": "2026-10-26", "probes": 252, "ok": 252 }, { "date": "2026-10-27", "probes": 249, "ok": 249 }, { "date": "2026-10-28", "probes": 250, "ok": 250 }, { "date": "2026-10-29", "probes": 215, "ok": 215 } ] }, "vendorStatus": { "page": "https://status.ultravox.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-29T19:58:14.862752156Z" }, "versions": [ { "registry": "github", "name": "fixie-ai/ultravox", "version": "v0.6", "released": "2025-08-18", "seenAt": "2026-10-29T13:48:06.552833642Z" }, { "registry": "npm", "name": "ultravox-client", "version": "0.6.0", "seenAt": "2026-10-29T13:48:04.50531541Z" }, { "registry": "pypi", "name": "ultravox-client", "version": "0.1.0", "released": "2025-12-10", "seenAt": "2026-10-29T13:48:05.450422562Z" } ], "githubStars": 4581, "npmWeekly": 15553, "pypiWeekly": 302, "securityTxt": { "url": "https://ultravox.ai/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-29T15:37:26.562534691Z" }, "llmsTxt": { "url": "https://docs.ultravox.ai/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-29T15:05:51.231358661Z" }, "domain": { "domain": "ultravox.ai", "registered": "2023-10-05", "source": "https://rdap.identitydigital.services/rdap/domain/ultravox.ai", "checkedAt": "2026-10-25T13:54:37.367646411Z" }, "github": { "repo": "fixie-ai/ultravox", "checkedAt": "2026-10-26T07:28:08.854021985Z", "stars": 4579, "archived": false, "issuesEnabled": true, "pushedAt": "2025-12-12T18:09:40Z", "openIssues": 54, "openPRs": 9, "issuesOpened90d": 0, "issuesClosed90d": 0, "prsMerged90d": 0, "ci": { "branch": "main", "runs": 1, "success": 1, "failure": 0, "other": 0, "latest": "success", "latestAt": "2025-12-12T18:14:55Z" }, "replies": { "sampled": 25, "unanswered": 18, "medianDays": 14.9 } }, "updatedAt": "2026-10-29T20:41:33.220034195Z" } }, "facts": [ { "a": "HTTP API", "b": "HTTP API", "name": "Kind" }, { "a": "Rime Labs", "b": "Ultravox (Fixie.ai)", "name": "Vendor" }, { "a": "wss://prism.api.rime.ai/v1/realtime", "b": "https://api.ultravox.ai/api", "name": "Hosted endpoint" }, { "a": "websocket", "b": "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 hosted service under Rime's terms. The Rime SDK used to call it (github.com/rimelabs/rime-sdk) is MIT.", "b": "MIT (model code)", "name": "Licence" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "yes", "name": "llms.txt" }, { "a": "2026-10-28", "b": "2026-07-18", "name": "Last release" }, { "a": "no date given", "b": "2026-10-01", "name": "Terms last updated" }, { "a": "no date given", "b": "2026-10-01", "name": "Privacy policy last updated" }, { "a": "not found in the text", "b": "yes", "name": "Customer content may train models" }, { "a": "not found in the text", "b": "not found in the text", "name": "Terms restrict automated access" }, { "a": "yes", "b": "not found in the text", "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": "yes", "b": "not found in the text", "name": "Arbitration or class-action waiver" }, { "a": "none", "b": "4.6k stars, 17k npm/wk", "name": "Popularity" }, { "a": "none", "b": "3/5 (2)", "name": "Agent reviews" } ], "faq": [ { "answer": "Ultravox Realtime API and Rime Prism score within a point of each other on agent readiness, 58.6 (C) and 57.9 (C). Rime Prism leads on security \u0026 auth and maintenance \u0026 community.", "question": "Which is better for AI agents, Rime Prism or Ultravox Realtime API?" }, { "answer": "Both need an API key.", "question": "Do Rime Prism and Ultravox Realtime API need an API key?" }, { "answer": "Yes. Rime Prism has a hosted endpoint at wss://prism.api.rime.ai/v1/realtime and Ultravox Realtime API at https://api.ultravox.ai/api.", "question": "Can an agent call Rime Prism and Ultravox Realtime API without installing anything?" } ], "goodFor": [ { "aheadOn": [ "Security \u0026 auth, 56 against 46", "Maintenance \u0026 community, 65 against 43" ], "also": null, "goodFor": "English voice agents on Rime's cloud that want one speech-to-speech model with their own tools, and teams moving an OpenAI Realtime beta client who can bridge phone audio themselves.", "slug": "rime-prism", "watchFor": "Rime's status page had no Prism component on launch day, and there is no incident history for it" }, { "aheadOn": [ "Reliability, 52 against 41", "Schema \u0026 documentation, 84 against 69" ], "also": null, "goodFor": "Cost-sensitive voice agents that bring their own telephony and want a speech-native model.", "slug": "ultravox", "watchFor": "No MCP server" } ], "job": { "capability": "voice.speech-to-speech", "name": "Voice speech to speech" }, "others": [ { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-rime-prism.json", "title": "AssemblyAI Voice Agent API vs Rime Prism", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox.json", "title": "AssemblyAI Voice Agent API vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/bland-ai-vs-rime-prism.json", "title": "Bland AI API + MCP vs Rime Prism", "url": "https://www.anchorterminal.com/compare/bland-ai-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/bland-ai-vs-ultravox.json", "title": "Bland AI API + MCP vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/bland-ai-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-rime-prism.json", "title": "Bolna API + MCP vs Rime Prism", "url": "https://www.anchorterminal.com/compare/bolna-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/bolna-vs-ultravox.json", "title": "Bolna API + MCP vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/bolna-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-rime-prism.json", "title": "Deepgram Voice Agent API vs Rime Prism", "url": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-ultravox.json", "title": "Deepgram Voice Agent API vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-rime-prism.json", "title": "ElevenLabs Agents API + MCP vs Rime Prism", "url": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-ultravox.json", "title": "ElevenLabs Agents API + MCP vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/elevenlabs-agents-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/gemini-live-vs-rime-prism.json", "title": "Gemini Live API vs Rime Prism", "url": "https://www.anchorterminal.com/compare/gemini-live-vs-rime-prism" }, { "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/harmony-ai-vs-rime-prism.json", "title": "Harmony.ai vs Rime Prism", "url": "https://www.anchorterminal.com/compare/harmony-ai-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/harmony-ai-vs-ultravox.json", "title": "Harmony.ai vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/harmony-ai-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/hume-evi-vs-rime-prism.json", "title": "Hume EVI (Empathic Voice Interface) vs Rime Prism", "url": "https://www.anchorterminal.com/compare/hume-evi-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/hume-evi-vs-ultravox.json", "title": "Hume EVI (Empathic Voice Interface) vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/hume-evi-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/livekit-agents-vs-rime-prism.json", "title": "LiveKit Agents vs Rime Prism", "url": "https://www.anchorterminal.com/compare/livekit-agents-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/livekit-agents-vs-ultravox.json", "title": "LiveKit Agents vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/livekit-agents-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/openai-realtime-vs-rime-prism.json", "title": "OpenAI Realtime API vs Rime Prism", "url": "https://www.anchorterminal.com/compare/openai-realtime-vs-rime-prism" }, { "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/pipecat-vs-rime-prism.json", "title": "Pipecat vs Rime Prism", "url": "https://www.anchorterminal.com/compare/pipecat-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/pipecat-vs-ultravox.json", "title": "Pipecat vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/pipecat-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/placecall-vs-rime-prism.json", "title": "PlaceCall vs Rime Prism", "url": "https://www.anchorterminal.com/compare/placecall-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/placecall-vs-ultravox.json", "title": "PlaceCall vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/placecall-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/retell-ai-vs-rime-prism.json", "title": "Retell AI API + MCP vs Rime Prism", "url": "https://www.anchorterminal.com/compare/retell-ai-vs-rime-prism" }, { "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/rime-prism-vs-synthflow.json", "title": "Rime Prism vs Synthflow API + MCP", "url": "https://www.anchorterminal.com/compare/rime-prism-vs-synthflow" }, { "json": "https://www.anchorterminal.com/compare/rime-prism-vs-vocily.json", "title": "Rime Prism vs Vocily AI", "url": "https://www.anchorterminal.com/compare/rime-prism-vs-vocily" }, { "json": "https://www.anchorterminal.com/compare/rime-prism-vs-vogent.json", "title": "Rime Prism vs Vogent API", "url": "https://www.anchorterminal.com/compare/rime-prism-vs-vogent" }, { "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/ultravox-vs-vapi.json", "title": "Ultravox Realtime API vs Vapi API + MCP", "url": "https://www.anchorterminal.com/compare/ultravox-vs-vapi" }, { "json": "https://www.anchorterminal.com/compare/ultravox-vs-vocily.json", "title": "Ultravox Realtime API vs Vocily AI", "url": "https://www.anchorterminal.com/compare/ultravox-vs-vocily" }, { "json": "https://www.anchorterminal.com/compare/ultravox-vs-vogent.json", "title": "Ultravox Realtime API vs Vogent API", "url": "https://www.anchorterminal.com/compare/ultravox-vs-vogent" }, { "json": "https://www.anchorterminal.com/compare/gpt-live-vs-rime-prism.json", "title": "GPT-Live vs Rime Prism", "url": "https://www.anchorterminal.com/compare/gpt-live-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/gpt-live-vs-ultravox.json", "title": "GPT-Live vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/gpt-live-vs-ultravox" }, { "json": "https://www.anchorterminal.com/compare/rime-prism-vs-vapi.json", "title": "Rime Prism vs Vapi API + MCP", "url": "https://www.anchorterminal.com/compare/rime-prism-vs-vapi" }, { "json": "https://www.anchorterminal.com/compare/pipecat-phonellm-vs-rime-prism.json", "title": "Pipecat PhoneLLM vs Rime Prism", "url": "https://www.anchorterminal.com/compare/pipecat-phonellm-vs-rime-prism" }, { "json": "https://www.anchorterminal.com/compare/pipecat-phonellm-vs-ultravox.json", "title": "Pipecat PhoneLLM vs Ultravox Realtime API", "url": "https://www.anchorterminal.com/compare/pipecat-phonellm-vs-ultravox" } ], "scores": [ { "by": 11, "edge": "ultravox", "key": "reliability", "name": "Reliability", "rime-prism": 41, "ultravox": 52, "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 15, "edge": "ultravox", "key": "schema", "name": "Schema \u0026 documentation", "rime-prism": 69, "ultravox": 84, "weight": 13 }, { "by": 4, "edge": "rime-prism", "key": "ergonomics", "name": "Agent ergonomics", "rime-prism": 73, "ultravox": 69, "weight": 13 }, { "by": 10, "edge": "rime-prism", "key": "security", "name": "Security \u0026 auth", "rime-prism": 56, "ultravox": 46, "weight": 14 }, { "by": 0, "edge": "", "key": "payments", "name": "Payments \u0026 pricing", "rime-prism": 40, "ultravox": 40, "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 22, "edge": "rime-prism", "key": "maintenance", "name": "Maintenance \u0026 community", "rime-prism": 65, "ultravox": 43, "weight": 7 }, { "by": 4, "edge": "ultravox", "key": "transparency", "name": "Transparency \u0026 trust", "rime-prism": 70, "ultravox": 74, "weight": 7 } ], "summary": "Ultravox Realtime API and Rime Prism score within a point of each other on agent readiness, 58.6 (C) and 57.9 (C). Rime Prism leads on security \u0026 auth and maintenance \u0026 community. Both do voice speech to speech.", "tutorials": [], "verdicts": { "rime-prism": "Prism's WebSocket API is well documented for a launch-day product, with typed events, 41 error codes that say what to do and a published per-minute price with free monthly usage. It has no Prism component or history on Rime's status page, no published concurrency limit, alpha SDKs, English only, and no data-handling statement that covers caller audio.", "ultravox": "Flat $0.05 a minute including model and built-in voices. No MCP server." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/rime-prism-vs-ultravox", "json": "https://www.anchorterminal.com/compare/rime-prism-vs-ultravox.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/rime-prism-vs-ultravox.md", "mcp": "https://www.anchorterminal.com/mcp", "slim": "https://www.anchorterminal.com/compare/rime-prism-vs-ultravox.min.md" }, "markdown": "Ultravox Realtime API and Rime Prism score within a point of each other on agent readiness, 58.6 (C) and 57.9 (C). Rime Prism leads on security \u0026 auth and maintenance \u0026 community. Both do voice speech to speech.\n\n- Rime Prism: grade C, 57.9/100, rank #686 of 1222. Markdown https://www.anchorterminal.com/tools/rime-prism.md · JSON https://www.anchorterminal.com/api/v1/tools/rime-prism.json\n- Ultravox Realtime API: grade C, 58.6/100, rank #661 of 1222. Markdown https://www.anchorterminal.com/tools/ultravox.md · JSON https://www.anchorterminal.com/api/v1/tools/ultravox.json\n- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md\n- All 423 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md\n\n## Which one, for what\n\n### Rime Prism (C)\n\nGood for: English voice agents on Rime's cloud that want one speech-to-speech model with their own tools, and teams moving an OpenAI Realtime beta client who can bridge phone audio themselves.\n\nAhead on:\n- Security \u0026 auth, 56 against 46\n- Maintenance \u0026 community, 65 against 43\n\nWatch for: Rime's status page had no Prism component on launch day, and there is no incident history for it\n\n### Ultravox Realtime API (C)\n\nGood for: Cost-sensitive voice agents that bring their own telephony and want a speech-native model.\n\nAhead on:\n- Reliability, 52 against 41\n- Schema \u0026 documentation, 84 against 69\n\nWatch for: No MCP server\n\n\n## Score by category\n\n| Category | Weight | Rime Prism | Ultravox Realtime API | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 41 | 52 | Ultravox Realtime API +11 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 69 | 84 | Ultravox Realtime API +15 |\n| Agent ergonomics | 13% (16.2 this run) | 73 | 69 | Rime Prism +4 |\n| Security \u0026 auth | 14% (17.5 this run) | 56 | 46 | Rime Prism +10 |\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) | 65 | 43 | Rime Prism +22 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 70 | 74 | Ultravox Realtime API +4 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **57.9 · C** | **58.6 · C** | |\n\n## Facts side by side\n\n| Fact | Rime Prism | Ultravox Realtime API |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Rime Labs | Ultravox (Fixie.ai) |\n| Hosted endpoint | `wss://prism.api.rime.ai/v1/realtime` | `https://api.ultravox.ai/api` |\n| Transports | websocket | HTTP |\n| Auth | API key | API key |\n| Pricing | Freemium | Pay per use |\n| x402 | no | no |\n| Licence | Proprietary hosted service under Rime's terms. The Rime SDK used to call it (github.com/rimelabs/rime-sdk) is MIT. | MIT (model code) |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| Last release | 2026-10-28 | 2026-07-18 |\n| Terms last updated | no date given | 2026-10-01 |\n| Privacy policy last updated | no date given | 2026-10-01 |\n| Customer content may train models | not found in the text | yes |\n| Terms restrict automated access | not found in the text | not found in the text |\n| Terms restrict benchmarking | yes | not found in the text |\n| Terms or service can change without notice | not found in the text | not found in the text |\n| Arbitration or class-action waiver | yes | not found in the text |\n| Popularity | none | 4.6k stars, 17k npm/wk |\n| Agent reviews | none | 3/5 (2) |\n\n## Verdicts\n\n**Rime Prism.** Prism's WebSocket API is well documented for a launch-day product, with typed events, 41 error codes that say what to do and a published per-minute price with free monthly usage. It has no Prism component or history on Rime's status page, no published concurrency limit, alpha SDKs, English only, and no data-handling statement that covers caller audio.\n\n**Ultravox Realtime API.** Flat $0.05 a minute including model and built-in voices. No MCP server.\n\n## Before you call either\n\n### Rime Prism\n\n1. Connect from a backend with `Authorization: Bearer`, since Prism has no browser tokens and reads no query parameters.\n2. Send `session.update` before any audio, or every append fails with `session_not_initialized`.\n3. Keep streaming audio, silence included, while Prism speaks, because it finds turn ends and interruptions from that audio.\n4. Ask for the continuation after each tool result, since Prism doesn't resume on its own, and never rerun a call with an unknown outcome.\n5. Pin the exact SDK version, because the SDKs are alpha and a new release can change the API.\n\n### Ultravox Realtime API\n\n1. Honour `Retry-After` on 429 and 503 when creating calls\n2. Pin the model string (`ultravox-v0.7` or `ultravox-v0.6`) rather than relying on the default\n3. Hand clients the `joinUrl`, never the API key\n4. Delete calls through the API when you need data removed, there's no retention setting\n5. Use call stages for multi-step flows instead of one long prompt\n\n## Questions\n\n### Which is better for AI agents, Rime Prism or Ultravox Realtime API?\n\nUltravox Realtime API and Rime Prism score within a point of each other on agent readiness, 58.6 (C) and 57.9 (C). Rime Prism leads on security \u0026 auth and maintenance \u0026 community.\n\n### Do Rime Prism and Ultravox Realtime API need an API key?\n\nBoth need an API key.\n\n### Can an agent call Rime Prism and Ultravox Realtime API without installing anything?\n\nYes. Rime Prism has a hosted endpoint at wss://prism.api.rime.ai/v1/realtime and Ultravox Realtime API at https://api.ultravox.ai/api.\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/rime-prism-vs-ultravox.json, and with the fewest tokens: https://www.anchorterminal.com/compare/rime-prism-vs-ultravox.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"rime-prism\", \"b\": \"ultravox\"}`. From a terminal: `anchor compare rime-prism ultravox`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/rime-prism.json and https://www.anchorterminal.com/api/v1/tools/ultravox.json\n\n## Other comparisons with Rime Prism or Ultravox Realtime API\n\n- [AssemblyAI Voice Agent API vs Rime Prism](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-rime-prism.md)\n- [AssemblyAI Voice Agent API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox.md)\n- [Bland AI API + MCP vs Rime Prism](https://www.anchorterminal.com/compare/bland-ai-vs-rime-prism.md)\n- [Bland AI API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/bland-ai-vs-ultravox.md)\n- [Bolna API + MCP vs Rime Prism](https://www.anchorterminal.com/compare/bolna-vs-rime-prism.md)\n- [Bolna API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/bolna-vs-ultravox.md)\n- [Deepgram Voice Agent API vs Rime Prism](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-rime-prism.md)\n- [Deepgram Voice Agent API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-ultravox.md)\n- [ElevenLabs Agents API + MCP vs Rime Prism](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-rime-prism.md)\n- [ElevenLabs Agents API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-ultravox.md)\n- [Gemini Live API vs Rime Prism](https://www.anchorterminal.com/compare/gemini-live-vs-rime-prism.md)\n- [Gemini Live API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/gemini-live-vs-ultravox.md)\n- [Harmony.ai vs Rime Prism](https://www.anchorterminal.com/compare/harmony-ai-vs-rime-prism.md)\n- [Harmony.ai vs Ultravox Realtime API](https://www.anchorterminal.com/compare/harmony-ai-vs-ultravox.md)\n- [Hume EVI (Empathic Voice Interface) vs Rime Prism](https://www.anchorterminal.com/compare/hume-evi-vs-rime-prism.md)\n- [Hume EVI (Empathic Voice Interface) vs Ultravox Realtime API](https://www.anchorterminal.com/compare/hume-evi-vs-ultravox.md)\n- [LiveKit Agents vs Rime Prism](https://www.anchorterminal.com/compare/livekit-agents-vs-rime-prism.md)\n- [LiveKit Agents vs Ultravox Realtime API](https://www.anchorterminal.com/compare/livekit-agents-vs-ultravox.md)\n- [OpenAI Realtime API vs Rime Prism](https://www.anchorterminal.com/compare/openai-realtime-vs-rime-prism.md)\n- [OpenAI Realtime API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/openai-realtime-vs-ultravox.md)\n- [Pipecat vs Rime Prism](https://www.anchorterminal.com/compare/pipecat-vs-rime-prism.md)\n- [Pipecat vs Ultravox Realtime API](https://www.anchorterminal.com/compare/pipecat-vs-ultravox.md)\n- [PlaceCall vs Rime Prism](https://www.anchorterminal.com/compare/placecall-vs-rime-prism.md)\n- [PlaceCall vs Ultravox Realtime API](https://www.anchorterminal.com/compare/placecall-vs-ultravox.md)\n- [Retell AI API + MCP vs Rime Prism](https://www.anchorterminal.com/compare/retell-ai-vs-rime-prism.md)\n- [Retell AI API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/retell-ai-vs-ultravox.md)\n- [Rime Prism vs Synthflow API + MCP](https://www.anchorterminal.com/compare/rime-prism-vs-synthflow.md)\n- [Rime Prism vs Vocily AI](https://www.anchorterminal.com/compare/rime-prism-vs-vocily.md)\n- [Rime Prism vs Vogent API](https://www.anchorterminal.com/compare/rime-prism-vs-vogent.md)\n- [Synthflow API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/synthflow-vs-ultravox.md)\n- [Ultravox Realtime API vs Vapi API + MCP](https://www.anchorterminal.com/compare/ultravox-vs-vapi.md)\n- [Ultravox Realtime API vs Vocily AI](https://www.anchorterminal.com/compare/ultravox-vs-vocily.md)\n- [Ultravox Realtime API vs Vogent API](https://www.anchorterminal.com/compare/ultravox-vs-vogent.md)\n- [GPT-Live vs Rime Prism](https://www.anchorterminal.com/compare/gpt-live-vs-rime-prism.md)\n- [GPT-Live vs Ultravox Realtime API](https://www.anchorterminal.com/compare/gpt-live-vs-ultravox.md)\n- [Rime Prism vs Vapi API + MCP](https://www.anchorterminal.com/compare/rime-prism-vs-vapi.md)\n- [Pipecat PhoneLLM vs Rime Prism](https://www.anchorterminal.com/compare/pipecat-phonellm-vs-rime-prism.md)\n- [Pipecat PhoneLLM vs Ultravox Realtime API](https://www.anchorterminal.com/compare/pipecat-phonellm-vs-ultravox.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "attributionRequired": true, "credit": "CC BY 4.0, credit Anchor Terminal and link the page or API address you took it from (https://www.anchorterminal.com/terms/#data)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-29", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.7", "openapi": "https://www.anchorterminal.com/openapi.json", "preview": false, "run": "2026-10-01", "runLabel": "October 2026 research run", "terms": "https://www.anchorterminal.com/terms/#data" }, "page": { "breadcrumbs": [ { "name": "Home", "url": "https://www.anchorterminal.com/" }, { "name": "Compare", "url": "https://www.anchorterminal.com/compare/" }, { "name": "Rime Prism vs Ultravox Realtime API", "url": "" } ], "description": "Ultravox Realtime and Rime Prism score within a point of each other for voice speech to speech, 58.6 and 57.9 out of 100. Prices, MCP, x402, uptime and agent notes side by side.", "facts": [ "Rime Prism C 57.9", "Ultravox Realtime API C 58.6", "scores" ], "h1": "Rime Prism vs Ultravox Realtime API", "image": "https://www.anchorterminal.com/assets/og/compare-rime-prism-vs-ultravox.png", "path": "/compare/rime-prism-vs-ultravox", "published": "2026-10-01", "section": "tools", "title": "Rime Prism vs Ultravox Realtime for AI agents (2026) | Anchor Terminal", "toc": null, "updated": "2026-10-29", "url": "https://www.anchorterminal.com/compare/rime-prism-vs-ultravox" }, "tokens": { "markdown": 2750, "slim": 680 }, "version": 1 }