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Cartesia vs Sesame

A side-by-side comparison of Cartesia and Sesame, two Voice tools, drawn from Ignaite's continuously-verified listings.

Compared from listings verified as of

Cartesia

Voice

Low-latency streaming text-to-speech for real-time voice.

View Cartesia

Sesame

Voice

Conversational voice companion chasing "voice presence."

View Sesame

At a glance

Feature comparison of Cartesia and Sesame
AttributeCartesiaSesame
CategoryVoiceVoice
Pricing (differs)FREEMIUMFREE
License (differs)ProprietaryOpen source
DeploymentCloudCloud
Platforms (differs)APIWeb
Model support (differs)Single model (proprietary)Self-contained (on-device)
Vendor (differs)CartesiaSesame
Capabilities (differs)
  • Voice agent
  • Speech synthesis (TTS)
  • Transcription (STT)
  • Voice cloning
  • Voice agent
  • Speech synthesis (TTS)
  • Companion chat

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

Sesame

Open-sourced its CSM-1B voice model under Apache 2.0 while keeping the viral Maya/Miles companions a hosted demo.

  • Open Apache-2.0 CSM-1B base model
  • Lifelike, natural conversational pacing
  • Free real-time web demo
  • Founder pedigree (Oculus co-creator)
  • Demo only; no production API yet
  • Companions not self-hostable
  • Early-stage product

When to pick which

Both cover Voice agent and Speech synthesis (TTS).

Pick Cartesia if you need Transcription (STT) and Voice cloning.

  • Transcription (STT) (secondary capability)
  • Voice cloning (secondary capability)

Pick Sesame if you need Companion chat.

  • Companion chat (secondary capability)

They share capabilities, but each leads with different ones as a headline job:

Cartesia is built around Speech synthesis (TTS).

  • Speech synthesis (TTS) (primary capability)

Sesame is built around Voice agent.

  • Voice agent (primary capability)

They also differ on:

Pricing
FREEMIUM · FREE
License
Proprietary · Open source
Platforms
API · Web
Model support
Single model (proprietary) · Self-contained (on-device)
Cartesia detailsSesame detailsAll Voice apps