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
| Attribute | Cartesia | Vapi |
|---|---|---|
| Category | Voice | Voice |
| Pricing | FREEMIUM | FREEMIUM |
| License | Proprietary | Proprietary |
| Deployment | Cloud | Cloud |
| Platforms (differs) | API | API, Web |
| Model support (differs) | Single model (proprietary) | Multi-model |
| Vendor (differs) | Cartesia | Vapi |
| Capabilities (differs) |
|
|
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
When to pick which
Both cover Voice agent.
Pick Cartesia if you need Speech synthesis (TTS), Transcription (STT), and Voice cloning.
- Speech synthesis (TTS) (primary capability)
- Transcription (STT) (secondary capability)
- Voice cloning (secondary capability)
Pick Vapi if you need Tool / function calling and Multi-model access.
- Tool / function calling (secondary capability)
- Multi-model access (secondary capability)
Vapi leans on Voice agent as a headline capability; Cartesia treats it as secondary.
- Voice agent (primary capability)
They also differ on:
- Platforms
- API · API, Web
- Model support
- Single model (proprietary) · Multi-model