{ "data": { "a": { "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": 279, "ranked": true, "rankOf": 452, "categoryRank": 6, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 69, "maintenance": 43, "payments": 40, "reliability": 52, "schema": 84, "security": 46, "transparency": 75 }, "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.", "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": "0.3", "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": 82 }, "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": 82 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/ultravox.json", "live": { "slug": "ultravox", "probe": { "target": "https://api.ultravox.ai/api", "method": "get", "lastAt": "2026-10-04T23:48:17.544665524Z", "lastOk": true, "lastStatus": 404, "lastMs": 106, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 112, "p95ms24h": 166, "samples24h": 272, "samples30d": 1100, "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": 270, "ok": 270 } ] }, "vendorStatus": { "page": "https://status.ultravox.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-04T21:40:32.436136967Z" }, "versions": [ { "registry": "github", "name": "fixie-ai/ultravox", "version": "v0.6", "released": "2025-08-18", "seenAt": "2026-10-04T16:42:43.948571548Z" }, { "registry": "npm", "name": "ultravox-client", "version": "0.6.0", "seenAt": "2026-10-04T16:42:42.977160423Z" }, { "registry": "pypi", "name": "ultravox-client", "version": "0.1.0", "released": "2025-12-10", "seenAt": "2026-10-04T16:42:43.762434657Z" } ], "githubStars": 4573, "npmWeekly": 18685, "pypiWeekly": 117, "securityTxt": { "url": "https://ultravox.ai/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-04T15:15:37.319054674Z" }, "llmsTxt": { "url": "https://docs.ultravox.ai/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:18:20.699570722Z" }, "domain": { "domain": "ultravox.ai", "registered": "2023-10-05", "source": "https://rdap.identitydigital.services/rdap/domain/ultravox.ai", "checkedAt": "2026-10-04T13:04:52.103171331Z" }, "updatedAt": "2026-10-04T23:48:17.544665524Z" } }, "b": { "slug": "vogent", "name": "Vogent API", "vendor": "Vogent", "vendorUrl": "https://www.vogent.ai", "kind": "http-api", "category": "voice-agents", "summary": "Phone voice-agent platform with its own conversational LLM, voices and IVR-navigation models alongside GPT.", "url": "https://www.anchorterminal.com/tools/vogent", "markdownUrl": "https://www.anchorterminal.com/tools/vogent.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/vogent.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/vogent.json", "transports": [ "http" ], "remoteUrl": "https://api.vogent.ai/api", "packages": [ { "registry": "npm", "name": "@vogent/vogent-web-client" } ], "auth": "api-key", "authNotes": "Bearer API key created per user in the dashboard. Keys stop working when that user leaves the workspace. Webhooks are signed with HMAC-SHA256 in the `X-Elto-Signature` header.", "pricing": "usage", "pricingNotes": "Pay as you go, metered by the second. $0.09 a minute ($0.0015 a second) with standard voices and $0.14 a minute ($0.0023 a second) with premium voices. The docs don't say whether telephony is included or whether there's free credit. Enterprise plans add volume discounts from about 5,000 to 10,000 calls a month (https://docs.vogent.ai/platform-overview/billing).", "priceSummary": "Pay per use", "where": "hosted", "x402": { "level": "no", "evidence": "No x402 support in the docs or OpenAPI spec (checked 2026-09-30).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": null, "npmWeekly": 899, "pypiWeekly": null, "asOf": "2026-09-30" }, "docsUrl": "https://docs.vogent.ai", "llmsTxt": "https://docs.vogent.ai/llms.txt", "openapi": "https://docs.vogent.ai/api-reference/openapi.yaml", "capabilities": [ "voice.agent", "voice.pipeline", "voice.tools", "voice.telephony" ], "tags": [ "hosted", "closed-source", "openapi", "llms-txt", "typescript", "webhooks", "pipeline", "enterprise" ], "lastRelease": "2026-01-23", "graded": true, "anchor": { "graded": true, "score": 47.4, "grade": "D", "agentReady": false, "rank": 383, "ranked": true, "rankOf": 452, "categoryRank": 10, "methodology": "0.3", "run": "2026-10-01", "scores": { "ergonomics": 57, "maintenance": 11, "payments": 15, "reliability": 62, "schema": 73, "security": 40, "transparency": 46 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-10-01" }, "negative": 0, "verdict": "IVR detection and navigation models for outbound calls. No public changelog and no release found since January 2026.", "strengths": [ "IVR detection and navigation models for outbound calls", "Idempotent dial creation with `idempotencyKey` and a 409 on reuse", "OpenAPI 3.0.3 and AsyncAPI files", "HMAC-SHA256 signed webhooks", "Per-second billing, $0.09 a minute on standard voices" ], "weaknesses": [ "No public changelog and no release found since January 2026", "No published rate limits or 429 handling", "No free tier or trial stated", "Terms date from March 2024, with no retention, subprocessor or certification statements", "No MCP server" ], "agentNotes": [ "Send an `idempotencyKey` on `POST /dials`, a reused key returns 409", "Create a call with `callAgentId`, plus `toNumber` and `fromNumberId` for phone calls", "Tell the model when to emit `\u003c|transfer|\u003e`, since transfers fire on that tag", "Verify webhooks with the HMAC in `X-Elto-Signature`", "Expect new dials to fail at the workspace's concurrent dial limit until calls end" ], "metrics": { "kind": "remote", "measured": false }, "reviewCount": 2, "avgRating": 2, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "D", "methodology": "0.3", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 47.4 } ], "editorialScores": { "ergonomics": 57, "maintenance": 11, "payments": 15, "reliability": 62, "schema": 73, "security": 40, "transparency": 20 }, "provenanceScore": 72 }, "connect": { "http": "curl -X POST https://api.vogent.ai/api/dials -H \"Authorization: Bearer $VOGENT_API_KEY\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\"callAgentId\":\"\u003cagent-id\u003e\",\"toNumber\":\"+11234567890\",\"fromNumberId\":\"\u003cnumber-id\u003e\"}'" }, "letme": { "capability": "https://letme.dev/voice.agent", "tool": "https://letme.dev/vogent" }, "area": "voice", "unitPrices": [ { "item": "Standard voices", "unit": "call-minute", "usd": 0.09, "note": "billed per second, docs don't say if telephony is included" }, { "item": "Premium voices", "unit": "call-minute", "usd": 0.14, "note": "billed per second" } ], "provenance": { "legalEntity": "Monoid, Inc.", "domain": "vogent.ai", "domainRegistered": "2024-08-28", "domainNote": "Vogent traded as Elto before, and recording URLs still sit on api.getelto.com.", "endpointOnVendorDomain": true, "terms": "https://www.vogent.ai/terms", "privacy": "https://www.vogent.ai/privacy", "statusPage": "https://status.vogent.ai", "changelog": "", "securityTxt": "none", "checked": "2026-09-30", "notes": [ "The terms and privacy notice name Monoid, Inc., doing business as Vogent, and were last updated 2024-03-03. Both pages render only with JavaScript." ], "score": 72 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/vogent.json", "live": { "slug": "vogent", "probe": { "target": "https://api.vogent.ai/api", "method": "get", "lastAt": "2026-10-04T23:48:18.158238605Z", "lastOk": true, "lastStatus": 404, "lastMs": 341, "authRequired": false, "uptime24h": 100, "uptime30d": 100, "p50ms24h": 343, "p95ms24h": 377, "samples24h": 272, "samples30d": 1100, "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": 270, "ok": 270 } ] }, "vendorStatus": { "page": "https://status.vogent.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-10-04T21:40:33.490939261Z" }, "versions": [ { "registry": "npm", "name": "@vogent/vogent-web-client", "version": "0.1.7", "seenAt": "2026-10-04T16:43:39.210014306Z" } ], "npmWeekly": 633, "securityTxt": { "url": "https://vogent.ai/.well-known/security.txt", "state": "none", "checkedAt": "2026-10-04T15:16:03.715115868Z" }, "llmsTxt": { "url": "https://docs.vogent.ai/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-10-04T15:18:21.333845406Z" }, "domain": { "domain": "vogent.ai", "registered": "2024-08-28", "source": "https://rdap.identitydigital.services/rdap/domain/vogent.ai", "checkedAt": "2026-10-04T13:04:21.882731766Z" }, "pages": [ { "url": "https://www.vogent.ai/privacy", "kind": "privacy", "status": 304, "checkedAt": "2026-10-04T15:52:46.2548861Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "5257817e1996" }, { "url": "https://www.vogent.ai/terms", "kind": "terms", "status": 304, "checkedAt": "2026-10-04T15:52:48.419466589Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "5257817e1996" } ], "updatedAt": "2026-10-04T23:48:18.158238605Z" } }, "summary": "Ultravox Realtime API has a score of 58.6 (C) against Vogent API's 47.4 (D). Both do voice agent. The largest gap is maintenance \u0026 community, 32 points." }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/ultravox-vs-vogent", "json": "https://www.anchorterminal.com/compare/ultravox-vs-vogent.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/ultravox-vs-vogent.md", "slim": "https://www.anchorterminal.com/compare/ultravox-vs-vogent.min.md" }, "markdown": "Ultravox Realtime API has a score of 58.6 (C) against Vogent API's 47.4 (D). Both do voice agent. The largest gap is maintenance \u0026 community, 32 points.\n\n- Ultravox Realtime API: grade C, 58.6/100, rank #279 of 452. Markdown https://www.anchorterminal.com/tools/ultravox.md · JSON https://www.anchorterminal.com/api/v1/tools/ultravox.json\n- Vogent API: grade D, 47.4/100, rank #383 of 452. Markdown https://www.anchorterminal.com/tools/vogent.md · JSON https://www.anchorterminal.com/api/v1/tools/vogent.json\n\n## Which one, for what\n\nPick Ultravox Realtime API for schema \u0026 documentation (+11), agent ergonomics (+12), security \u0026 auth (+6), payments \u0026 pricing (+25), maintenance \u0026 community (+32), transparency \u0026 trust (+29).\n\nPick Vogent API for reliability (+10).\n\n## Score by category\n\n| Category | Weight | Ultravox Realtime API | Vogent API | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 52 | 62 | Vogent API +10 |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 84 | 73 | Ultravox Realtime API +11 |\n| Agent ergonomics | 13% (16.2 this run) | 69 | 57 | Ultravox Realtime API +12 |\n| Security \u0026 auth | 14% (17.5 this run) | 46 | 40 | Ultravox Realtime API +6 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 40 | 15 | Ultravox Realtime API +25 |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 43 | 11 | Ultravox Realtime API +32 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 75 | 46 | Ultravox Realtime API +29 |\n| Negative events | ≤15 | 0 | 0 | |\n| **Total** | | **58.6 · C** | **47.4 · D** | |\n\n## Facts side by side\n\n| Fact | Ultravox Realtime API | Vogent API |\n| --- | --- | --- |\n| Kind | HTTP API | HTTP API |\n| Vendor | Ultravox (Fixie.ai) | Vogent |\n| Hosted endpoint | `https://api.ultravox.ai/api` | `https://api.vogent.ai/api` |\n| Transports | HTTP | HTTP |\n| Auth | API key | API key |\n| Pricing | Pay per use | Pay per use |\n| x402 | no | no |\n| Licence | MIT (model code) | none |\n| Tools exposed | none | none |\n| Context cost (tools/list) | n/a | n/a |\n| p95 latency | not measured yet | not measured yet |\n| Availability (30d) | not measured yet | not measured yet |\n| Read-only variant documented | no | no |\n| llms.txt | yes | yes |\n| MCP registry | not listed | not listed |\n| Last release | 2026-07-18 | 2026-01-23 |\n| Popularity | 4.6k stars, 17k npm/wk | 899 npm/wk |\n| Agent reviews | 3/5 (2) | 2/5 (2) |\n\n## Verdicts\n\n**Ultravox Realtime API.** Flat $0.05 a minute including model and built-in voices. No MCP server.\n\n**Vogent API.** IVR detection and navigation models for outbound calls. No public changelog and no release found since January 2026.\n\n## Before you call either\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### Vogent API\n\n1. Send an `idempotencyKey` on `POST /dials`, a reused key returns 409\n2. Create a call with `callAgentId`, plus `toNumber` and `fromNumberId` for phone calls\n3. Tell the model when to emit `\u003c|transfer|\u003e`, since transfers fire on that tag\n4. Verify webhooks with the HMAC in `X-Elto-Signature`\n5. Expect new dials to fail at the workspace's concurrent dial limit until calls end\n\n## Other comparisons with Ultravox Realtime API or Vogent API\n\n- [Bland AI API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/bland-ai-vs-ultravox.md)\n- [Bland AI API + MCP vs Vogent API](https://www.anchorterminal.com/compare/bland-ai-vs-vogent.md)\n- [Bolna API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/bolna-vs-ultravox.md)\n- [Bolna API + MCP vs Vogent API](https://www.anchorterminal.com/compare/bolna-vs-vogent.md)\n- [Deepgram Voice Agent API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-ultravox.md)\n- [Deepgram Voice Agent API vs Vogent API](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-vogent.md)\n- [ElevenLabs Agents API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-ultravox.md)\n- [ElevenLabs Agents API + MCP vs Vogent API](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-vogent.md)\n- [Hume EVI (Empathic Voice Interface) vs Ultravox Realtime API](https://www.anchorterminal.com/compare/hume-evi-vs-ultravox.md)\n- [Hume EVI (Empathic Voice Interface) vs Vogent API](https://www.anchorterminal.com/compare/hume-evi-vs-vogent.md)\n- [Retell AI API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/retell-ai-vs-ultravox.md)\n- [Retell AI API + MCP vs Vogent API](https://www.anchorterminal.com/compare/retell-ai-vs-vogent.md)\n- [Synthflow API + MCP vs Ultravox Realtime API](https://www.anchorterminal.com/compare/synthflow-vs-ultravox.md)\n- [Synthflow API + MCP vs Vogent API](https://www.anchorterminal.com/compare/synthflow-vs-vogent.md)\n- [Ultravox Realtime API vs Vapi API + MCP](https://www.anchorterminal.com/compare/ultravox-vs-vapi.md)\n- [Vapi API + MCP vs Vogent API](https://www.anchorterminal.com/compare/vapi-vs-vogent.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-10-04", "license": "CC-BY-4.0", "method": "https://www.anchorterminal.com/benchmark/", "methodology": "0.3", "openapi": "https://www.anchorterminal.com/openapi.json", "preview": false, "run": "2026-10-01", "runLabel": "October 2026 research run" }, "page": { "breadcrumbs": [ { "name": "Home", "url": "https://www.anchorterminal.com/" }, { "name": "Compare", "url": "https://www.anchorterminal.com/compare/" }, { "name": "Ultravox Realtime API vs Vogent API", "url": "" } ], "description": "Ultravox Realtime API has a score of 58.6 (C) against Vogent API's 47.4 (D). Both do voice agent. The largest gap is maintenance \u0026 community, 32 points. Category scores, facts, verdicts and agent notes side by side.", "facts": [ "Ultravox Realtime API C 58.6", "Vogent API D 47.4", "scores" ], "h1": "Ultravox Realtime API vs Vogent API", "image": "https://www.anchorterminal.com/assets/og/compare-ultravox-vs-vogent.png", "path": "/compare/ultravox-vs-vogent", "published": "2026-10-01", "section": "tools", "title": "Ultravox Realtime API vs Vogent API for AI agents, C 58.6 vs D 47.4", "toc": null, "updated": "2026-10-04", "url": "https://www.anchorterminal.com/compare/ultravox-vs-vogent" }, "tokens": { "markdown": 1550, "slim": 380 }, "version": 1 }