AssemblyAI API pricing
Research-driven STT with the Universal and Slam-1 models and a deep audio-intelligence add-on stack (sentiment, topics, LeMUR LLM).
Free tier or trialBilled per minute (usage-based)·Verified Jun 27, 2026
Free tier
$50 one-time credit
Plans and prices
| Plan | Price | What it covers |
|---|---|---|
| Free credits | $50 free | No credit card required; 5 new streams/min concurrency limit. Self-serve signup. |
| Universal-2 (async STT) | $0.15/hr | Pre-recorded transcription, billed per second; lowest base rate tier. |
| Universal-3 Pro (async STT) | $0.21/hr | Higher-accuracy async model (~5.6% mean WER, keyterm prompting). |
| Universal-Streaming | $0.15/hr | Real-time English/multilingual; billed per WebSocket session duration. |
| Voice Agent API | $4.50/hr ($0.075/min) | All-inclusive STT + LLM + TTS + turn detection + tool calling. |
| Enterprise | Custom | 99.9% uptime SLA, custom SLOs, volume pricing, committed-use; 600M+ monthly inference calls capacity. |
What to watch for on the bill
- Add-on features (diarization, entity detection, redaction, translation) stack on the base rate, pushing effective cost well above the $0.15/hr headline (~$0.35/hr in independent estimates)
- Cost becomes expensive at high audio volume for usage-heavy apps
- Billing-UX friction reported (e.g. difficulty removing a card or disabling autopay)
The pricing page, as we saw it
Source: https://www.assemblyai.com/pricing. Prices change. Confirm on the vendor page before you commit.
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