{ "name": "Ultravox", "slug": "ultravox", "website_url": "https://www.ultravox.ai", "vendor_description": "\"Real-time, speech native voice AI\"", "categories": [ "voice-agents" ], "summary": "Ultravox is a speech-native voice AI API for building real-time conversational agents, targeting developers who need inbound and outbound telephony automation, AI receptionists, or voice-enabled web and mobile apps. Pricing is usage-based at $0.05 per minute with 30 free minutes included and self-serve signup, though pay-as-you-go accounts are hard-capped at 5 concurrent calls and the outbound call scheduler requires a Pro plan or higher. The platform integrates with Twilio, Telnyx, Plivo, and jambonz for telephony but does not provision phone numbers itself. SDKs are available for JavaScript, Python, React Native, Flutter, Android, and iOS.", "capabilities": { "supported_actions": [ "realtime_conversation", "speech_to_speech", "inbound_telephony", "outbound_telephony", "sip_trunking", "call_transfer", "function_calling", "tool_calling", "interruption_handling", "byo_voice", "knowledge_base", "batch_calling", "call_recording", "web_widget", "webhook_events", "voice_cloning", "rag_knowledge_base", "call_stages", "outbound_call_scheduler", "websocket_streaming" ], "supported_regions": [ "United States" ], "supported_languages": [ "Arabic", "Bulgarian", "Chinese", "Czech", "Danish", "Dutch", "English", "Finnish", "French", "German", "Greek", "Hindi", "Hungarian", "Italian", "Japanese", "Polish", "Portuguese", "Romanian", "Russian", "Slovak", "Spanish", "Swedish", "Tamil", "Turkish", "Ukrainian", "Vietnamese" ], "input_types": [ "audio stream", "PSTN phone call", "SIP", "WebRTC", "WebSocket" ], "output_types": [ "audio stream", "call transcript", "webhook events", "call recording", "structured call summary", "real-time transcriptions" ], "webhooks_supported": true, "sandbox_available": false, "sdk_languages": [ "JavaScript", "Python", "React Native", "Flutter", "Kotlin (Android)", "Swift (iOS)" ], "mcp_server_available": false }, "integration": { "api_style": "rest", "base_url": "https://api.ultravox.ai/api/", "api_version": "0.1.0", "versioning_scheme": "none", "stability": "ga", "deprecation_policy_url": "https://docs.ultravox.ai/changelog/news", "auth_methods": [ "api_key" ], "auth_docs_url": "https://docs.ultravox.ai/api-reference/introduction", "idempotency_supported": false, "error_format": "vendor-specific", "webhook_signing": "hmac_sha256", "webhook_events_url": "https://docs.ultravox.ai/webhooks/available-webhooks", "rate_limit_requests": 5, "rate_limit_window": "concurrent calls", "sdk_packages": [ { "package": "ultravox-client", "language": "JavaScript", "official": true, "repo_url": "https://github.com/fixie-ai/ultravox-client-sdk-js" }, { "package": "ultravox-client", "language": "Python", "official": true, "repo_url": "https://github.com/fixie-ai/ultravox-client-sdk-python" }, { "package": "ultravox-react-native", "language": "React Native", "official": true, "repo_url": "https://github.com/fixie-ai/ultravox-client-sdk-react-native" }, { "package": "ultravox_client", "language": "Flutter", "official": true, "repo_url": "https://github.com/fixie-ai/ultravox-client-sdk-flutter" }, { "package": null, "language": "Kotlin (Android)", "official": true, "repo_url": "https://github.com/fixie-ai/ultravox-client-sdk-android" }, { "package": null, "language": "Swift (iOS)", "official": true, "repo_url": "https://github.com/fixie-ai/ultravox-client-sdk-ios" } ], "mcp_url": null, "quickstart_url": "https://docs.ultravox.ai/gettingstarted/quickstart/agent-console" }, "pricing": { "pricing_model": "usage_based", "has_published_pricing": true, "starting_price_usd": "0.0500", 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"one-time", "currency": "USD", "source_url": "https://www.ultravox.ai/pricing" }, { "plan": "Pro", "item": "Platform fee", "amount_usd": "100.0000", "amount_percent": null, "per": "month", "currency": "USD", "source_url": "https://www.ultravox.ai/pricing" }, { "plan": "Pro", "item": "Voice agent orchestration", "amount_usd": "0.0500", "amount_percent": null, "per": "minute", "currency": "USD", "source_url": "https://www.ultravox.ai/pricing" }, { "plan": "Pro", "item": "SIP telephony", "amount_usd": "0.0048", "amount_percent": null, "per": "minute", "currency": "USD", "source_url": "https://www.ultravox.ai/pricing" }, { "plan": "Pro", "item": "Threads input tokens (uncached)", "amount_usd": "2.0000", "amount_percent": null, "per": "1M tokens", "currency": "USD", "source_url": "https://www.ultravox.ai/pricing" }, { "plan": "Pro", "item": "Threads output tokens", "amount_usd": "15.0000", "amount_percent": null, "per": "1M tokens", "currency": "USD", "source_url": "https://www.ultravox.ai/pricing" }, { "plan": "Enterprise", "item": "Voice agent orchestration", "amount_usd": null, "amount_percent": null, "per": "minute", "currency": "USD", "source_url": "https://www.ultravox.ai/pricing" } ] }, "compliance": { "soc2": null, "hipaa": null, "gdpr": null, "iso_27001": null, "pci_dss": null, "sla_published": false, "sla_url": null, "data_retention_policy_url": "https://www.ultravox.ai/privacy", "documented_rate_limits": "Account level: 500 req/s; API key level: 200 req/s. Call creation: PAYGO 5/sec + 30/min, Pro 10/sec + 120/min, Scale 30/sec + 360/min. Concurrency: PAYGO hard cap 5 concurrent calls; Pro no hard cap (subject to infrastructure limits); Scale no hard cap with up to 100 priority calls.", "known_restrictions": [ "Pay-as-you-go accounts hard capped at 5 concurrent calls", "Outbound call scheduler only available on Pro plan and above", "BYO-LLM not supported - platform uses its own open-weight speech-native models", "Telephony is BYO (Twilio, Telnyx, Plivo, jambonz) - no built-in PSTN number provisioning", "SDK message payload limit: 15-16KB max", "No published SLA - Terms of Service explicitly disclaim uptime guarantees", "Data stored and processed primarily in US" ] }, "developer": { "docs_url": "https://docs.ultravox.ai/overview", "api_reference_url": null, "openapi_spec_url": null, "postman_collection_url": null, "changelog_url": null, "status_page_url": "https://status.ultravox.ai", "llms_txt_url": null, "markdown_docs_url": null, "rendering": "static" }, "adoption": { "launched_at": "2024-09-04", "ga_date": "2024-09-04", "github_stars": null, "github_stars_at": null, "notable_customers": [ "11x" ] }, "scores": { "agent_friendliness": 20, "pricing_transparency": 85, "setup_speed": 60, "docs_quality": 15, "procurement_friction": 85, "trust_readiness": 0, "best_for": [ "Teams needing broad API coverage out of the box", "Cost-sensitive teams - low, transparent entry price" ], "avoid_if": [ "You want to try it free before paying", "You have strict compliance requirements" ] }, "sources": [ { "field": "vendor_description", "url": "https://www.ultravox.ai", "excerpt": "Real-time, speech native voice AI", "confidence": "high" }, { "field": "pricing_model", "url": "https://www.ultravox.ai/pricing", "excerpt": "Pay as You Go: $0/month ... $0.05 per minute after the free allotment ... 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Webhooks – Real-time event notifications", "confidence": "high" }, { "field": "sdk_languages", "url": "https://docs.ultravox.ai/sdk-reference/introduction", "excerpt": "there are currently six implementations of the SDK available", "confidence": "high" }, { "field": "sandbox_available", "url": "https://www.ultravox.ai/pricing", "excerpt": "Unlimited playground calls", "confidence": "medium" }, { "field": "soc2", "url": "https://www.ultravox.ai/privacy", "excerpt": "Our Service are hosted in the United States and intended for visitors located within the United States.", "confidence": "medium" }, { "field": "sla_published", "url": "https://www.ultravox.ai/terms", "excerpt": "FIXIE DOES NOT WARRANT THAT THE SERVICE OR ANY PORTION OF THE SERVICE...WILL BE UNINTERRUPTED, SECURE, OR FREE OF ERRORS", "confidence": "high" }, { "field": "documented_rate_limits", "url": "https://docs.ultravox.ai/gettingstarted/concurrency", "excerpt": "Any account not on a monthly or annual subscription is limited to five concurrent calls. 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Per API key: 200 requests/second ... Free/PAYGO: 5/second, 30/minute ... Pro: 10/second, 120/minute ... Scale: 30/second, 360/minute", "confidence": "high" }, { "field": "known_restrictions", "url": "https://docs.ultravox.ai/gettingstarted/concurrency", "excerpt": "Pay-as-you-go accounts: Any account not on a monthly or annual subscription is limited to five concurrent calls", "confidence": "high" }, { "field": "self_serve_signup", "url": "https://docs.ultravox.ai/api-reference/introduction", "excerpt": "To get an API key, sign-up for a free account and then generate an API key", "confidence": "high" }, { "field": "input_types", "url": "https://docs.ultravox.ai/gettingstarted/how-ultravox-works", "excerpt": "The platform embraces a bring-your-own-telephony (BYOT) approach, allowing users to integrate with SIP trunking, Twilio, or other providers", "confidence": "high" }, { "field": "base_url", "url": "https://docs.ultravox.ai/api-reference/introduction", "excerpt": "The Ultravox API base url is https://api.ultravox.ai/api/", "confidence": "high" }, { "field": "api_style", "url": "https://docs.ultravox.ai/api-reference/introduction", "excerpt": "The Ultravox REST API is used to create calls; you will need to use one of our client SDKs to join and end calls", "confidence": "high" }, { "field": "sdk_packages", "url": "https://docs.ultravox.ai/sdk-reference/introduction", "excerpt": "there are currently six implementations of the SDK available", "confidence": "high" }, { "field": "quickstart_url", "url": "https://docs.ultravox.ai", "excerpt": "A quickstart guide is referenced at /gettingstarted/quickstart/agent-console", "confidence": "high" }, { "field": "webhook_signing", "url": "https://docs.ultravox.ai/webhooks/securing-webhooks", "excerpt": "Verify that this timestamp is recent (e.g. within the last minute) to prevent replay attacks.", "confidence": "high" }, { "field": "rate_limit_requests", "url": "https://docs.ultravox.ai/gettingstarted/concurrency", "excerpt": "Any account not on a monthly or annual subscription is limited to five concurrent calls.", "confidence": "high" }, { "field": "starting_price_usd", "url": "https://www.ultravox.ai/pricing", "excerpt": "$0.05 per minute", "confidence": "high" }, { "field": "launched_at", "url": "https://docs.ultravox.ai/changelog/news", "excerpt": "September 4, 2024: Initial public launch with pricing at $0.05/min, resume calls capability, and voice cloning features", "confidence": "high" }, { "field": "data_retention_policy_url", "url": "https://www.ultravox.ai/privacy", "excerpt": "retain personal information about you for as long as you have an account with us or as otherwise necessary to provide you with our Service", "confidence": "high" }, { "field": "versioning_scheme", "url": "https://docs.ultravox.ai/api-reference/introduction", "excerpt": "No versioning scheme is mentioned in the provided content.", "confidence": "medium" }, { "field": "stability", "url": "https://docs.ultravox.ai/changelog/news", "excerpt": "September 4, 2024: Initial public launch with pricing at $0.05/min", "confidence": "medium" }, { "field": "auth_docs_url", "url": "https://docs.ultravox.ai/gettingstarted/quickstart/apikeys", "excerpt": "Creating an API Key", "confidence": "high" }, { "field": "error_format", "url": "https://docs.ultravox.ai/api-reference/introduction", "excerpt": "Too many API requests can trigger an error with status code 429", "confidence": "medium" }, { "field": "price_basis", "url": "https://www.ultravox.ai/pricing", "excerpt": "$0.05 per minute including text-to-speech", "confidence": "high" }, { "field": "auth_docs_url", "url": "https://docs.ultravox.ai/api-reference/introduction", "excerpt": "When making API calls, pass your key in using the X-API-Key header. 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