Cartesia vs Phonic
A side-by-side comparison of Cartesia and Phonic, two Voice tools, drawn from Ignaite's continuously-verified listings.
Compared from listings verified as of
At a glance
The honest brief
Cartesia
State-space Sonic models hit sub-100ms first audio — the latency floor for real-time voice agent loops.
- Streaming over WebSocket for fast first audio
- State-space architecture, not transformer
- Streaming-first WebSocket protocol depth
- Cost-competitive at scale
- Long-form expressive texture trails ElevenLabs
- Fewer voices than ElevenLabs catalog
- API-only, no end-user app
Phonic
Runs one proprietary speech-to-speech model at sub-300ms latency instead of an STT→LLM→TTS chain, with eval and observability built in for voice agents.
- Reliable tool calling for voice agents
- Natural turn-taking, low latency
- Built-in eval and observability
- Self-host / containerized option
- Enterprise-focused, no public free tier
- Pricing not published
- Younger than larger voice platforms