AssemblyAI API
Speech recognition + audio intelligence, transcription, sentiment, summaries
Freemium
✓ Verified
🇺🇸 United States
AssemblyAI goes beyond basic transcription to offer a full audio intelligence platform. Alongside highly accurate speech-to-text in 99+ languages, it provides sentiment analysis, speaker diarization, topic detection, content moderation, PII redaction, and automatic chapter generation via a single API. Real-time streaming transcription supports live audio feeds. Widely used by podcast platforms, meeting tools, call centers, and media companies. One of the best free tiers in the speech API space at $50 in credit.
API Details
Auth Method
API Key
Pricing Model
Freemium
Free Tier
Yes — $50 free credit on signup
Rate Limit
Concurrent file limit by plan
Format
REST / WebSocket / JSON
Versioning
v2
SLA / Uptime
99.5%
Compliance
SOC 2, GDPR, HIPAA
Geographic Restrictions
Global
Last Verified
2026-02-20
Categories
Frequently Asked Questions
AssemblyAI offers more than transcription u2014 it includes speaker diarisation (who said what), sentiment analysis, content moderation, chapter detection, entity recognition, and PII redaction all in one API call. This makes it significantly more powerful than raw transcription APIs like Whisper for building production audio intelligence applications.
AssemblyAI pricing: Core transcription is $0.37 per hour of audio. Speaker diarisation adds $0.52/hour. Sentiment analysis and entity detection add $0.13/hour each. PII redaction is $0.26/hour. There is a free tier with limited usage. Compared to alternatives, AssemblyAI is competitively priced for the combined feature set it offers.
Yes. AssemblyAI offers a Streaming Speech-to-Text API that provides real-time transcription via WebSocket connections with under 300ms latency. This is suitable for live captioning, voice agents, and real-time meeting intelligence. Real-time pricing is $0.65 per hour, slightly higher than asynchronous transcription.
LeMUR is AssemblyAI's LLM framework built on top of transcription. It lets you ask questions about audio content u2014 summarise a meeting, extract action items, answer questions about a podcast u2014 using Claude or other LLMs via AssemblyAI's unified API. This simplifies building audio intelligence features without managing separate transcription and LLM integrations.