Master AssemblyAI with our step-by-step tutorial, detailed feature walkthrough, and expert tips.
Sign up at assemblyai.com to get your API key and $50 in free credits. Install the AssemblyAI SDK for your language (Python, Node.js, Java, etc.) or use the REST API directly. Submit your first audio file for async transcription using the /v2/transcript endpoint and poll for results. Enable audio intelligence features like speaker diarization or sentiment analysis by adding parameters to your transcription request. Explore LeMUR to query your transcripts with natural language and integrate real
time streaming via WebSocket for live applications.
💡 Quick Start: Follow these 2 steps in order to get up and running with AssemblyAI quickly.
Explore the key features that make AssemblyAI powerful for speech ai apis workflows.
Production-grade speech-to-text model at $0.21/hour async and $0.45/hour real-time, supporting 99+ languages with automatic detection. Consistently ranks in the top tier of the Open ASR Leaderboard for English conversational audio with 5-8% word error rates.
WebSocket-based streaming transcription with sub-300ms end-to-end latency, delivering both partial predictions (real-time guesses) and confident final results. This dual-output architecture is what makes conversational voice agents feel responsive during natural dialogue.
Bundled speaker diarization, sentiment analysis, PII redaction, entity detection, auto-chapters, and content moderation in a single API call. Speaker diarization identifies who spoke when across multi-person conversations. PII redaction automatically removes sensitive data like SSNs and credit card numbers.
Natural language querying of transcripts using Claude and other frontier LLMs, accessed through the same API as transcription. Ask 'What action items were discussed?' or 'Summarize the customer's complaints' and receive structured responses without building a separate LLM pipeline.
SOC 2 Type II certification, HIPAA compliance with signed BAAs, and EU data residency for GDPR workflows. Configurable retention policies including zero-retention processing where audio and transcripts are deleted immediately after processing completes.
AssemblyAI's Universal-3 Pro model typically achieves 5-8% word error rates on conversational English audio, benchmarking competitively with Google's latest models and Deepgram Nova-3. On phone-call audio with background noise, AssemblyAI often edges ahead due to training emphasis on real-world conversational data. Accuracy on non-English languages is more variable and should be tested for your specific use case.
A typical 10-minute customer service call costs $0.035 in base transcription ($0.21/hour prorated). Adding sentiment analysis, entity detection, and PII redaction pushes that to roughly $0.05 per call. A voice agent handling 500 calls per day would cost approximately $25/day in base transcription plus add-on fees, with volume discounts available through enterprise agreements.
Universal-3 Pro supports 99+ languages with automatic language detection, but quality varies significantly by language. English, Spanish, French, and German perform at production-grade accuracy with full audio intelligence support. Less common languages may have higher word error rates and should be tested with representative audio samples before committing to production use.
LeMUR (Leveraging Large Language Models to Understand Recognized Speech) is AssemblyAI's framework for querying transcripts with natural language directly through the same API. Instead of transcribing, then separately sending output to an LLM, LeMUR handles both steps in a single API call with optimized context handling for audio-derived text, reducing latency and simplifying your architecture.
Yes. AssemblyAI offers HIPAA-compliant processing with signed BAAs for healthcare customers, SOC 2 Type II certification, and EU data residency for GDPR-regulated workflows. Built-in PII redaction automatically removes social security numbers, credit card numbers, and other sensitive data from transcripts. Zero-retention processing is available for maximum data privacy.
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Tutorial updated March 2026