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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 →

AssemblyAI pricing

Published rates: batch $0.0035/min · streaming $0.0075/min, verified Jul 20, 2026 (source).

AssemblyAI cost at monthly volume tiers
Monthly volumeBatch billStreaming bill
1K min/moSide project$3.50$7.50
10K min/moProduction app$35$75
100K min/moCall-center scale$350$750

Sticker rates only; diarization and PII redaction add-ons price in the stack builder. How we compute costs →

Fact sheet

Pricing
Pricing facts
Batch price per audio minute0.004 $/audio-minJul 20
Streaming price per audio minute0.008 $/audio-minJul 20
Pricing modelusageJul 20
Free tier quota$50 one-time signup credit, no credit card requiredJul 20
Published volume discountsCustom tiered pricing via sales; no published ratesJul 20
Concurrency on base planAsync: 200+ concurrent jobs; streaming: 100 new streams/minJul 20
Extra concurrency costCustom higher limits at no additional costJul 20
Capabilities
Capabilities facts
WER (third-party benchmark)3.02 % WERJul 20
WER (vendor-claimed)~5.6 % WERJul 20
Streaming latency (vendor-claimed)~150 msJul 20
Languages supported99Jul 20
Language auto-detection✓ YesJul 20
Speaker diarization◑ Paid add-onJul 20
Diarization add-on price per minute0 $/audio-minJul 20
PII redaction◑ Paid add-onJul 20
PII redaction add-on price per minute0.001 $/audio-minJul 20
Word-level timestamps✓ YesJul 20
Custom vocabulary / keyterm boosting✓ YesJul 20
Entity detection✓ YesJul 20
Sentiment analysis✓ YesJul 20
Summarization endpoint✓ YesJul 20
Speech translation✓ YesJul 20
Priced audio-intelligence add-ons13 per-hour add-ons (Speech Understanding + Guardrails)Jul 20
Compliance & trust
Compliance & trust facts
HIPAA BAA available✓ IncludedJul 20
SOC 2 Type II✓ YesJul 20
GDPR / EU data residency✓ YesJul 20
Self-host / on-prem option✓ YesJul 20
Build experience
Build experience facts
Official SDKsPython, JavaScript/Node (official)Jul 20
Max file size / duration5 GB / 10 hr per file; 2.2 GB via upload endpointJul 20
Supported audio formats30+ audio + video formats (mp3, wav, flac, m4a, mp4, mov)Jul 20
Websocket streaming API✓ YesJul 20

Considering a switch? Best AssemblyAI alternatives →

Voice agents in this stack

The engine is one layer: a voice agent hears through its transcription engine, but orchestration, telephony, and turn-taking come from the agent platform. Compare the platforms builders pair AssemblyAI with: Pipecat, OpenAI Realtime API, Twilio ConversationRelay, or the full voice-agent comparison →

Want it done for you?

AssemblyAI gets you a transcript; the bot that joins the call, labels speakers, and writes the summary is still your build. If that is more pipeline than you want to own, AI meeting notetakers do the whole job end to end: Otter.ai, Fireflies.ai, Fathom, or the full notetaker comparison.

AssemblyAI head-to-head

AssemblyAI vs Deepgram →won 3 · lost 0 · tied 3
Call CenterswonDeveloperswonDictationtieMedicaltieMeetingswonSelf-Hostedtie
DeveloperswonDictationtieMedicalwonMeetingswonSelf-HostedlostVoice Agentswon
AssemblyAI vs ElevenLabs Scribe →won 3 · lost 2 · tied 1
Call CenterswonDeveloperslostDictationtieMedicalwonSelf-HostedwonVoice Agentslost
AssemblyAI vs Speechmatics →won 3 · lost 2 · tied 2
Call CenterslostDeveloperslostDictationtieMedicalwonMeetingswonSelf-HostedtieVoice Agentswon
AssemblyAI vs Gladia →won 4 · lost 0 · tied 3
Call CenterswonDeveloperswonDictationtieMedicaltieMeetingswonSelf-HostedtieVoice Agentswon
AssemblyAI vs Rev AI →won 4 · lost 0 · tied 2
DeveloperstieDictationtieMedicalwonMeetingswonSelf-HostedwonVoice Agentswon
AssemblyAI vs Soniox →won 4 · lost 0 · tied 1
DictationtieMedicalwonMeetingswonSelf-HostedwonVoice Agentswon