Cartesia vs Vapi
A side-by-side comparison of Cartesia and Vapi, 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
Vapi
Solves the hard parts of phone agents — telephony, low-latency turn-taking and barge-in — while leaving STT/LLM/TTS fully pluggable.
- Telephony and interrupts handled
- Pluggable STT + LLM + TTS stack
- Fast to a working phone agent
- Generous developer free tier
- Per-minute costs stack across layers
- Latency depends on chosen models
- Complex configuration surface
- Cloud-only orchestration