Speech-to-Text API
Build voice AI apps with fast & accurate speech recognition
Multilingual speech-to-text with speaker diarization, real-time transcription, and LLM integrations for intelligence out of the box.
Free to try. No credit card required.
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Best-in-Class Models
Ultra-fast, ultra-accurate speech-to-text models
on real-world audio
Everything you need to build voice apps that outpace the competition
Insanely accurate & fast transcription
Best-in-class WER and low latency on real-world audio and live streams.
Real-time diarization
Identify and label speakers on all audio files.
Formatted transcripts
Directly integrate with LLMs for summarization, topic extraction, or CS workflows.
Secure & compliant
Guardrails including PII redaction and profanity filtering. Build HIPAA-ready apps with BAA, SOC 2.
Usage-based pricing
Pay-as-you-go from $0.15/hr with no commitments or minimums.
Speech recognition with insanely accurate results
Model | Overall Accuracy | Alphanumerics Missed (lower is better) | Medical Missed (lower is better) |
|---|---|---|---|
AssemblyAI Universal-3 Pro | 94.07% | 7.5% | 13.61% |
Deepgram Nova-3 | 92.01% | 18.69% | 16.95% |
Speech-to-text quality that speaks for itself.
AssemblyAI’s developer-first API lets you start testing in under a minute. Join 200k+ developers building next-generation Voice AI apps. Transcribe speech-to-text, identify and label speakers, redact sensitive info, and integrate with LLMs. All in one stack.
If you have an hour of content, the difference between 99% accuracy and 97% accuracy, it's a lot of time for that person to review. So you could cut down their workflow from taking half an hour, taking 20 minutes, taking 15 minutes– it's huge, right?
The 30-40% reduction in speech-to-text errors has significantly improved our production efficiency and client satisfaction. We've achieved industry-leading word error rates for non-English audio, which is critical for serving our enterprise clients.
The cost saving is literally the difference between being profitable or not for us, but beyond the economics, AssemblyAI gave us something invaluable: peace of mind. We can focus on building our product instead of worrying about infrastructure limits.
On 10 out of 10 onboarding calls, our customers are at some point telling us 'wow that insight was crisp'—and that's because of the accuracy we're getting from AssemblyAI.
Get started for free
Get $50 in free credits and production-ready Voice AI infrastructure from day one.
Frequently Asked Questions
AssemblyAI offers several state-of-the-art speech recognition models, each optimized for different use cases. Choose between pre-recorded and streaming models that best fits your needs based on accuracy, latency, cost, and language requirements. Universal-3 Pro is our newest model with the highest accuracy rates across all audio types.
Yes! With the free offer, you get $50 in credits to use towards AssemblyAI’s Speech-to-Text APIs. To add more credits, simply add a credit card to your account.
AssemblyAI’s Universal-3 Pro model leads our published benchmarks with a 94.07% Word Accuracy Rate and delivers near‑human accuracy, even on noisy or challenging audio.
Yes. AssemblyAI offers real-time Streaming Speech-to-Text via a secure WebSocket API, returning partial and final transcripts within a few hundred milliseconds. It’s optimized for ultra-low latency (~300 ms P50) and supports use cases like live captioning and voice agents
Yes! Sign up for a free account to access our no-code playground. Compare speech-to-text models, real-time transcription, and LLM Gateway to send your transcript directly to your chosen LLM for summarization and custom prompts.
Yes! Speaker detection is built into the API and you'll be able to label multiple speakers and identify them by name in your transcript.