Cartesia
Ultra-low-latency voice models built on state space models.
Full Cartesia record →Head to head
Cartesia vs AssemblyAI
Cartesia (Cartesia) and AssemblyAI (AssemblyAI) both sit in Audio. AssemblyAI is the cheaper entry point at Free tier · from $0.15/1M tok. AssemblyAI shipped more tracked changes in the last 30 days (8 vs 0). Every value below comes from the latest crawl of the vendors' own pages.
| Attribute | Cartesia Cartesia | AssemblyAI AssemblyAI |
|---|---|---|
| Segment | Audio | Audio |
| Version | Sonic 3 | Universal-3.6 Pro Realtime |
| Entry cost | Free tier · from $5/mo | Free tier · from $0.15/1M tok |
| Pricing tiers | — | Free Credits free · Universal-2 Async STT $0.15 · Universal-Streaming English / Multilingual $0.15 · Universal-3.5 Pro Async STT $0.21 · Universal-3.6 Pro Realtime STT $0.45 · Text-to-Speech (AssemblyAI-TTS-1) $15 |
| Model stack | Sonic 3 | AssemblyAI-TTS-1 · Claude · Claude 4.6 Sonnet · Claude 4.8 Opus · Gemini 2.5 Pro · Gemini 3.5 Flash · GPT-5.5 · Qwen3 Next 80B A3B · u3-rt-pro · Universal-2 · universal-3-6-pro · universal-3-pro · Universal-3.5 Pro · Universal-3.5 Pro Realtime · Universal-3.6 Pro Realtime · Universal-Streaming English · Universal-Streaming Multilingual |
| Context window | — | n/a |
| Public API | ||
| Routes models | ||
| Changes / 30d | 0 | 8 |
| Origin | Global | Global |
| Capabilities | Sub-100ms TTS, Voice cloning, Realtime API | Speaker diarization, Summarisation, Topic detection, PII redaction, LeMUR framework, Pre-recorded STT, Real-time STT, Voice Agent API |
AssemblyAI
Transcription plus summarisation, topic detection and speaker labels for developers.
Full AssemblyAI record →