Cartesia vs Retell AI
A side-by-side comparison of capabilities, autonomy, integrations, and pricing to help you choose.
Short answer: choose Cartesia if you want low-latency voice ai models and a platform for real-time voice agents (Assistant, freemium); choose Retell AI if you want platform to build, test, deploy, and monitor ai voice agents for calls (Autonomous agent, usage).
| Cartesia | Retell AI | |
|---|---|---|
| What it is | Low-latency voice AI models and a platform for real-time voice agents | Platform to build, test, deploy, and monitor AI voice agents for calls |
| Type | platform | platform |
| Autonomy | Assistant | Autonomous agent |
| Pricing | freemium · Free (20K credits/mo); Pro $5/mo | usage · $0.07/min voice engine (model + telephony billed on top); Enterprise from $8,000 |
| Best for | developers, enterprise | developers, smb, mid-market, enterprise |
| Deployment | saas, api, self-hosted, on-prem | saas, api |
| Modalities | text, voice, api, code | voice, text, api |
| Models | proprietary | model-agnostic, gpt, claude |
| Protocols | rest-api, function-calling | rest-api, function-calling |
| Integrations | LiveKit, Twilio, Pipecat, Vapi | Twilio, Telnyx, Vonage, ElevenLabs, PlayHT |
| Capabilities | 4 documented | 4 documented |
Cartesia
- +Genuinely differentiated state-space-model tech with best-in-class latency and on-device efficiency
- +Full stack (TTS, STT, cloning, and the Line agent platform) plus deep ecosystem integrations and self-hosted/VPC options
- +Strong technical credibility and capital, including NVIDIA backing
- -Younger and less battle-tested than ElevenLabs and Deepgram; the Line agent platform is barely a year old
- -Closed, proprietary models (no open weights for production Sonic/Ink), creating lock-in
Retell AI
- +Provider-flexible: bring your own telephony, voices, and LLM, or use Retell's built-in carrier
- +Structured Conversation Flow Agents (nodes and transitions) give fine control alongside looser prompt-based agents
- +Usage-based pricing with no mandatory base subscription and free credits to start; built-in testing and monitoring
- -Advertised $0.07/min covers only the voice engine; LLM, telephony, and international add to real per-minute cost
- -Building reliable structured flows for complex calls takes meaningful human setup
Which should you choose?
Cartesia is low-latency voice ai models and a platform for real-time voice agents, best for developers, enterprise. Retell AI is platform to build, test, deploy, and monitor ai voice agents for calls, best for developers, smb, mid-market, enterprise. The right choice depends on the autonomy level you want, your existing integrations, and your budget, all compared above.