AssemblyAI provides Voice AI models and APIs for speech-to-text, speech understanding, and voice applications. Its Speech Understanding API includes speaker diarization and identification, summaries, action items, sentiment analysis, key phrases, entity and topic detection, formatting, language detection, translation, PII redaction, and content moderation. AssemblyAI states that it covers 99 languages and translates into 86. Customers can use its managed cloud or self-host models inside their own environment. Integrations include Twilio, Zoom RTMS, Zapier, LangChain, and Vercel AI SDK, while its documentation includes Python and JavaScript SDK guidance. Listed protections include TLS 1.2+ encryption in transit, AES-256 encryption at rest, zero data retention, and an option to opt out of model training. AssemblyAI states that streaming and voice-agent latency is below 300ms. A free tier includes audio credits subject to connection and transcription limits. Usage-based plans are billed monthly; listed rates include $0.15 per hour for Universal-2 and $0.45 per hour for Universal-3.6 Pro Realtime.
Who it is for
AssemblyAI may suit developers building speech-to-text, speech-understanding, or voice applications through APIs. It also offers self-hosting for customers who want to run models in their own environment.
What is good
- Speech features include diarization, summaries, and sentiment analysis.
- States support for 99 languages.
- Offers managed-cloud and self-hosted deployment.
- Free tier includes audio credits.
- Monthly billing is based on actual usage.
What to know first
- Free tier has streaming and transcription limits.
- Universal-3.5 Pro Realtime is listed for 18 languages.
- Pay-as-you-go charges vary with usage.
Verdict
AssemblyAI offers a broad set of speech capabilities and usage-based plans, with a free tier subject to stated limits. Compare the language coverage and rates for each model to the needs of your application.
AssemblyAI plans and pricing
All plansCompared on transcription software
- Free plan
- No
- Languages supported
- 99 languages
- Speaker identification
- Yes
- Timestamp support
- Yes
- Export formats
- SRT, VTT
- API access
- Yes
