Cartesia vs Retell AI
Relationship
Cartesia's customer story says Retell AI added Cartesia as a primary voice provider for its voice agents.
1 shared capability — Across all their products, both list voice agent.
Ludbee capability tags · every product each company sellsShared product type — Both ship agent platform.
Ludbee product recordsCustomer — “Retell added Cartesia as a primary voice provider”
cartesia.ai · checked 2026-10-13Aligned comparison
Capability overlap
Shared · 1
Not verified for Retell AI · 2
Recorded for Cartesia. Retell AI’s product records say nothing either way — a missing record is not a missing capability.
Not verified for Cartesia · 3
Recorded for Retell AI. Cartesia’s product records say nothing either way — a missing record is not a missing capability.
Products, side by side
Hand-checked pairing
Cartesia
Agent platform
Cartesia's managed platform for building and running realtime voice agents: Ink speech-to-text, an LLM you choose and Sonic text-to-speech, with turn-taking, tool calling, telephony (SIP trunking) and built-in evaluations handled by the platform.
Retell AI
Agent platform
AI copilot on every page of the Retell dashboard: told in plain language what to change, it proposes edits to a voice or chat agent for approval, generates simulation tests from real calls, filters call and chat history to explain failures, and builds analytics charts.
Platform for building, deploying and monitoring AI voice agents that handle phone calls: call transfer to humans, appointment booking, IVR navigation, outbound call campaigns and post-call analysis.
Text counterpart of Retell's voice agents: businesses build AI chat agents with the same prompts, functions and knowledge bases, or convert a voice agent in one click, and deploy them in a website widget, over two-way SMS or through a chat API, billed per AI message.
No counterpart
Cartesia sells these in a stack layer with no product recorded for Retell AI yet — nothing on the other side to compare them against.
API service
Sonic (text-to-speech) and Ink (speech-to-text) are Cartesia's voice-generation models, sold via API to developers and enterprises building voice agents.