AssemblyAI Review

Accuracy-led voice AI API for developers and voice agents

Among the 43 speech-to-text tools we track, AssemblyAI has the 12th-widest language coverage - a fit for multilingual and localization projects.

See pricing

Facts verified Jul 20, 2026Try AssemblyAI →

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What we know about AssemblyAI

AssemblyAI is a speech-to-text apis platform: accuracy-led voice AI API for developers and voice agents. This profile tracks every AssemblyAI fact we have verified, each linked to a primary source and dated.

AssemblyAI does not publish a public per-minute rate we have been able to verify, so the price figure here stays blank until we can confirm one. We would rather show nothing than a guessed number; if you have a current AssemblyAI quote, it is the fastest way for us to close that gap.

On capabilities, AssemblyAI covers language auto-detection, word-level timestamps, custom vocabulary / keyterm boosting, entity detection, sentiment analysis, and summarization endpoint. Each of those is verified against AssemblyAI's own docs or dashboard, not marketing copy.

For compliance, with AssemblyAI: SOC 2 Type II is in place. If you are in a regulated space, confirm the current posture with AssemblyAI before you commit, since these change plan by plan.

AssemblyAI ranks the 12th-widest language coverage of the 43 speech-to-text tools we track, so where it lands for you depends on which of those matters more.

In total we track 31 verified facts for AssemblyAI today, each linking the primary source it came from so you can check our work - and vendor claims we have not measured ourselves are labeled as such on the AssemblyAI fact sheet below.

Reviewed by vsref Editorialfacts verified Jul 20, 2026Methodology →

Fact sheet

Every row independently verified

Pricing

Pricing facts
Batch price per audio minute	0.004 $/audio-min	Jul 20
Streaming price per audio minute	0.008 $/audio-min	Jul 20
Pricing model	usage	Jul 20
Free tier quota	$50 one-time signup credit, no credit card required	Jul 20
Published volume discounts	Custom tiered pricing via sales; no published rates	Jul 20
Concurrency on base plan	Async: 200+ concurrent jobs; streaming: 100 new streams/min	Jul 20
Extra concurrency cost	Custom higher limits at no additional cost	Jul 20

Capabilities

Capabilities facts
WER (third-party benchmark)	3.02 % WER	Jul 20
WER (vendor-claimed)	~5.6 % WER	Jul 20
Streaming latency (vendor-claimed)	~150 ms	Jul 20
Languages supported	99	Jul 20
Language auto-detection	✓ Yes	Jul 20
Speaker diarization	◑ Paid add-on	Jul 20
Diarization add-on price per minute	0 $/audio-min	Jul 20
PII redaction	◑ Paid add-on	Jul 20
PII redaction add-on price per minute	0.001 $/audio-min	Jul 20
Word-level timestamps	✓ Yes	Jul 20
Custom vocabulary / keyterm boosting	✓ Yes	Jul 20
Entity detection	✓ Yes	Jul 20
Sentiment analysis	✓ Yes	Jul 20
Summarization endpoint	✓ Yes	Jul 20
Speech translation	✓ Yes	Jul 20
Priced audio-intelligence add-ons	13 per-hour add-ons (Speech Understanding + Guardrails)	Jul 20

Compliance & trust

Compliance & trust facts
HIPAA BAA available	✓ Included	Jul 20
SOC 2 Type II	✓ Yes	Jul 20
GDPR / EU data residency	✓ Yes	Jul 20
Self-host / on-prem option	✓ Yes	Jul 20

Build experience

Build experience facts
Official SDKs	Python, JavaScript/Node (official)	Jul 20
Max file size / duration	5 GB / 10 hr per file; 2.2 GB via upload endpoint	Jul 20
Supported audio formats	30+ audio + video formats (mp3, wav, flac, m4a, mp4, mov)	Jul 20
Websocket streaming API	✓ Yes	Jul 20