tools
AssemblyAI
AssemblyAI provides APIs for transcribing, understanding, and building applications with spoken audio.
AssemblyAI offers speech-to-text APIs for recorded and realtime audio, plus speaker diarization, language detection, prompting, sentiment analysis, entity detection, summaries, redaction, and other speech-understanding features.
Developers use it for voice agents, meeting notetakers, call analytics, medical documentation, dictation, and contact-center tools. It is an API platform rather than a consumer transcription app; usage is billed based on audio processed or tokens used, with some features costing extra.
Features
- Transcribe recorded audio and video with Universal-3.5 Pro or Universal-2
- Transcribe live audio with realtime speech-to-text APIs
- Detect and label multiple speakers with speaker diarization
- Improve recognition with keyterms prompting and natural-language prompting
- Extract sentiment, entities, topics, translations, and summaries
- Apply PII redaction, profanity filtering, and content moderation
- Route transcripts to multiple language models through LLM Gateway
- Run voice agents through a single WebSocket API
Use cases
- Build realtime voice agents for customer support and sales
- Transcribe meetings and generate summaries, chapters, and action items
- Analyze customer calls for sentiment, topics, entities, and compliance
- Create ambient medical documentation and AI scribe workflows
- Add formatted speech input to dictation features
- Provide live coaching and compliance alerts to contact-center agents
Pros
Cons
Latest updates
- DeepSeek V4.1 Flash 1017 and Reflection Beam on LLM Gateway
Two more models are available through the LLM Gateway: DeepSeek V4.1 Flash 1017 and Beam.
- Fix: Summarization No Longer Fails on Long Audio
Summarization now runs with corrected prompting and a raised output limit, so results are no longer cut off on large audio files.
- Breaking: Transcript Polling Limited to 60 Requests per Minute Starting October 19
GET /v2/transcript/{transcript_id} is now rate-limited to 60 requests per minute for each combination of API key and transcript ID.
- Reduced Hallucinations on Silent Multichannel Audio
Voice-activity-based silence trimming is now enabled for all English multichannel transcription, reducing hallucinations caused by long silent stretches.
- Muse Spark Open Now Available on the LLM Gateway
Muse Spark Open is now available through the LLM Gateway as muse-spark-open and supports tool calling, structured outputs, and streaming.
Capabilities
- Text to speech — “Low-latency speech generation built for realtime conversation.” source
- Speech to text — “Transcribes recorded audio and video asynchronously across 99 languages, with support on speaker diarization, PII redaction, and more features.” source
- Many languages — “Get clean, customizable transcripts in 99 languages with industry-leading accuracy and natural language prompting.” source
- API — “Build directly against the raw HTTP and WebSocket API for full control over requests and responses.” source
Get it
Security
- SOC 2 Type II — “We maintain a SOC 2 Type 2 report covering security, availability, and confidentiality, audited annually by an independent firm.” source
- SOC 2 — “We maintain a SOC 2 Type 2 report covering security, availability, and confidentiality, audited annually by an independent firm.” source
- Not trained on your data — “Your data is never used to train or improve our models when you opt out.” source
Pricing
- Starting price
- Free
- Prices checked
- 2026-10-23
- Read
- by web search
Free
Free
- Up to 185 hours of pre-recorded transcription
- Up to 333 hours of streaming transcription
- No credit card required
Pay as you go
- $0.21 /hr
- $0.15 /hr
- $4.50/hr
- Universal-3.5 Pro: $0.21/hr
- Universal-2: $0.15/hr
- Voice Agent API: $4.50/hr (includes STT, LLM, TTS)
- Billed monthly based on actual usage
- No minimum commitments or contracts
Custom
Price on request
- Custom rate limits and concurrency
- Enterprise-grade flexibility
- Volume discounts available
- Contact sales for tailored pricing