Ultravox Agents
by Fixie.ai
Speech-native LLM and hosted agent runtime by Fixie.ai.
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TL;DR
Best for developers wanting an open speech-native LLM as the brain of their voice agent. Pricing: see vendor pricing.
Category
Transcription APIs
License
MIT
Stars
★ 4.5k
Last push
2025-12-12
Pricing
see vendor pricing
Platforms
Cloud, API
What it is
Ultravox is Fixie.ai's speech-native LLM that consumes audio directly without a separate ASR step, reducing pipeline latency. Fixie also offers a hosted agent runtime that wires Ultravox with TTS providers for end-to-end voice apps. The open weights variant gives developers an OSS path to speech-in LLMs.
Best for: Developers wanting an open speech-native LLM as the brain of their voice agent.
Watch out for: Newer entrant; production tooling less mature than OpenAI Realtime.
Watch out for: Newer entrant; production tooling less mature than OpenAI Realtime.
Features
| Speaker diarization | No |
| Word-level timestamps | No |
| Streaming / real-time | No |
| Languages supported | None |
| HIPAA eligible | No |
Links
Ultravox Agents vs Whipscribe
| Feature | Ultravox Agents | Whipscribe |
|---|---|---|
| Category | Transcription APIs | Transcription APIs |
| Pricing | Not verified | $4–$24 one-time packs (credits never expire) · $2 single unlock · 60 min free on signup |
| Speaker diarization | Not verified | Yes |
| Word timestamps | Not verified | Yes |
| Streaming | Not verified | No |
| Languages | — | 99 |
| Platforms | Cloud, API | Web, API, MCP |
Alternatives to Ultravox Agents
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