Speech-to-Text API
Build voice AI apps with fast & accurate Speech-to-Text
Multilingual speech-to-text with speaker diarization, AI guardrails, and LLM integrations out of the box. Build intelligent voice products in minutes without juggling multiple vendors.
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Best-in-Class Models
Ultra-fast, ultra-accurate audio-to-text
Everything you need to build voice apps that outpace the competition
Insanely Accurate & Fast
Best-in-class WER and low latency for real-world audio.
Multilingual Diarization
Automatically detects 99 languages and identifies speakers.
Formatted Transcripts
Directly integrate with LLMs for summarization, topic extraction, or CS workflows.
Secure & Compliant
Guardrails including PII redaction and profanity filtering. HIPAA-ready with BAA, SOC 2.
Priced to Scale
Pay-as-you-go from $0.15/hr with no commitments or minimums.
Speech recognition with insanely accurate results
Model | Overall | Alphanumerics | Proper Nouns |
|---|---|---|---|
AssemblyAI Universal | 93.32% | 4.00% | 13.87% |
Deepgram Nova-2 | 90.76% | 4.97% | 21.14% |
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 audio-to-text, identify 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.
Unlock the value of voice data
Get $50 in free credits and production-ready infrastructure from day one.
Frequently Asked Questions
Universal is AssemblyAI's high-accuracy model supporting 99 languages, built for general-purpose use cases. It offers strong out-of-the-box performance and supports features like speaker diarization and real-time streaming. Slam-1 is our most advanced speech language model, designed specifically for speech tasks. It uses a prompt-based architecture for deeper contextual understanding and allows domain-specific customization—no retraining needed. Perfect for legal, medical, and other specialized use cases. Universal-Streaming is an ultra-fast, ultra-accurate streaming speech-to-text model designed for voice agents.
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 model leads our published benchmarks with a 93.3% 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.
Multilingual speech-to-text with speaker diarization, AI guardrails, and LLM integrations out of the box. Build intelligent voice products in minutes without juggling multiple vendors.