AssemblyAI
Transcription plus summarisation, topic detection and speaker labels for developers.
Full AssemblyAI record →Head to head
AssemblyAI vs Cartesia
AssemblyAI (AssemblyAI) and Cartesia (Cartesia) both sit in Audio. AssemblyAI is the cheaper entry point at Free tier with $50 free credits, then pay-as-you-go starting at $0.15/hr for pre-recorded STT (Universal-2). AssemblyAI shipped more tracked changes in the last 30 days (5 vs 0). Every value below comes from the latest crawl of the vendors' own pages.
| Attribute | AssemblyAI AssemblyAI | Cartesia Cartesia |
|---|---|---|
| Segment | Audio | Audio |
| Version | Universal-3.5 Pro | Sonic 3 |
| Entry cost | Free tier with $50 free credits, then pay-as-you-go starting at $0.15/hr for pre-recorded STT (Universal-2) | Free tier · from $5/mo |
| Pricing tiers | Free Credits free | — |
| Model stack | 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-pro · Universal-3.5 Pro · Universal-3.5 Pro Realtime · Universal-Streaming English · Universal-Streaming Multilingual | Sonic 3 |
| Context window | n/a | — |
| Public API | ||
| Routes models | ||
| Changes / 30d | 5 | 0 |
| Origin | Global | Global |
| Capabilities | Speaker diarization, Summarisation, Topic detection, PII redaction, LeMUR framework, Pre-recorded STT, Real-time STT, Voice Agent API | Sub-100ms TTS, Voice cloning, Realtime API |
Cartesia
Ultra-low-latency voice models built on state space models.
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