AssemblyAI
Speech-to-text and voice AI infrastructure for developers building audio applications.
Pricing
About AssemblyAI
AssemblyAI is a voice AI infrastructure platform providing production-ready speech-to-text and voice agent APIs for developers. The platform offers multiple transcription options including pre-recorded, real-time, and synchronous speech-to-text APIs powered by the Universal-3.5 Pro model, supporting 99 languages with industry-leading accuracy. Beyond transcription, developers can leverage speech understanding capabilities to extract speaker identification, sentiment, chapters, and summaries, plus build voice agents with built-in turn detection and interruption handling. The platform is designed for developers, product teams, and enterprises building voice-enabled applications. AssemblyAI distinguishes itself through comprehensive infrastructure that scales from initial prototypes to processing millions of hours monthly, with global redundancy and enterprise-grade uptime. The company also provides additional tools like PII redaction guardrails and an LLM gateway for routing between multiple language models. A notable limitation is that while the platform supports many languages, implementation details for less common language support are not extensively documented.
At a glance
- Company
- AssemblyAI, Inc. (est. 2017)
- Platforms
- Web, API
- API
- Available
- Last verified
- July 2026
Who It's For
- •Developers building voice-enabled applications
- •Product teams creating voice AI features
- •Enterprises requiring scalable voice infrastructure
- •Companies in contact centers, medical, and compliance-heavy industries
- •Startups building conversational AI applications
How It Works
- 1Accepts audio input through multiple APIs: pre-recorded files, real-time streaming, or synchronous clips
- 2Processes audio using Universal-3.5 Pro speech model to generate accurate transcripts
- 3Extracts insights including speaker identification, sentiment analysis, chapters, and summaries
- 4For voice agents, provides real-time turn detection and interruption handling for natural conversation flow
- 5Offers PII redaction and content moderation applied inline to audio and transcripts
How to Use AssemblyAI
- 1Sign up for free account and get API credentials
- 2Choose appropriate API type based on use case (pre-recorded, real-time, sync, or voice agent)
- 3Import AssemblyAI SDK in your code (available in multiple languages)
- 4Pass audio data or stream to the selected API endpoint
- 5Receive structured transcripts and insights in response
- 6Use playground for no-code testing before implementation
Key Features
- •Universal-3.5 Pro speech recognition model with 36% improvement in close rates
- •Pre-recorded, real-time, and synchronous speech-to-text APIs
- •Voice Agent API with built-in turn detection and interruption handling
- •Speech Understanding API for extracting speaker ID, sentiment, chapters, summaries
- •99-language support
- •PII redaction and content moderation guardrails
- •LLM Gateway for routing between multiple language models (GPT, Claude, Gemini, community models)
- •Global redundancy and enterprise-grade uptime
- •Processing 2 million hours of audio daily
- •No concurrency limits, throttles, or forced commitments
Use Cases
- •Real-time transcription for communication platforms and voice agents
- •Meeting transcription, summarization, and conversation intelligence
- •Compliance monitoring and audit trail generation for regulated industries
- •Medical dictation and healthcare documentation
- •Content repurposing by transcribing audio/video for different formats
Pros & Cons
Advantages
- •Industry-leading accuracy with Universal-3.5 Pro model achieving 36% improvement in close rates
- •Comprehensive voice AI stack (transcription, understanding, agents) in single platform reducing integration complexity
- •True platform scalability with no concurrency limits or throttles, supporting from MVP to 400,000+ hours monthly
- •Global redundancy and enterprise-grade infrastructure processing 2 million hours of audio daily
Disadvantages
- •Real-time speech-to-text requires streaming capability which may have higher latency requirements than batch processing
- •Pricing model not transparently detailed on homepage, requiring contact with sales for enterprise quotes
- •Documentation for less common languages and advanced features appears limited in public resources
Alternatives
- Eden AI
- Google Cloud Speech-to-Text
- Amazon Transcribe
- Microsoft Azure Speech Services
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Frequently Asked Questions
What is AssemblyAI?
AssemblyAI is a voice AI infrastructure platform providing production-ready speech-to-text and voice agent APIs for developers. The platform offers multiple transcription options including pre-recorded, real-time, and synchronous speech-to-text APIs powered by the Universal-3.
How much does AssemblyAI cost?
AssemblyAI has a free plan; paid plans start at $0.15.
Is AssemblyAI free?
Yes, AssemblyAI offers a free plan you can start with.
What are the best AssemblyAI alternatives?
Popular AssemblyAI alternatives include Eden AI, Google Cloud Speech-to-Text, Amazon Transcribe.
What is AssemblyAI used for?
AssemblyAI is commonly used for Real-time transcription for communication platforms and voice agents, Meeting transcription, summarization, and conversation intelligence, Compliance monitoring and audit trail generation for regulated industries.
Does AssemblyAI have an API?
Yes, AssemblyAI offers an API for developers.
What platforms does AssemblyAI support?
AssemblyAI is available on Web, API.
Information Accuracy
Please note: While we regularly update all tool information including descriptions, features, pricing, and other details, this information may change over time as tools evolve and update their offerings. For the most current and accurate information, we recommend visiting the official website directly. Our goal is to provide you with comprehensive and up-to-date information to help you make informed decisions.