Speech-to-Text API

AssemblyAI

Industry-leading AI models to transcribe and understand speech with unmatched accuracy and scalability.

Overview

AssemblyAI offers state-of-the-art speech-to-text and speech understanding AI models designed for developers to build, ship, and scale voice AI applications with high accuracy, multilingual support, and advanced features like speaker diarization and contextual prompting.

Updated Oct 18, 2026

1 review

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5.0out of 5Rating breakdown

Rising Star
Taylor GJul 20, 2026
Recommends this tool
The speaker labels were probably my favorite feature in AssemblyAI. It made conversations much easier to follow and the AI summary saved me time when reviewing longer recordings.
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1 review

Community reviews

Sort:Write a review

5.0out of 5Rating breakdown

Rising Star
Taylor GJul 20, 2026
Recommends this tool
The speaker labels were probably my favorite feature in AssemblyAI. It made conversations much easier to follow and the AI summary saved me time when reviewing longer recordings.
Helpful1Not helpfulReport

Tried this tool? Share your experience.

Write a review

6 things

What AssemblyAI has

For developers

Programmatic access to the product's data and features for developers.
Run the software on your own servers instead of the vendor's cloud.
A ready-made set of instructions that helps an AI agent use a product.
A Model Context Protocol server that lets AI tools connect to and act on your data.
A toolkit that lets developers build on the product using their preferred programming language.

Hosting and storage

Vendor-provided online infrastructure for deploying and running software.

12 features

Key Features

Speech-to-Text
Get clean, customizable transcripts in 99 languages with industry-leading accuracy and natural language prompting.
Real-time transcription
Stream transcripts in real time with async-level accuracy, so your agent responds fast without mishearing the user.
Synchronous transcription
Send a short clip and get a finished, flagship-accuracy transcript back in the same response — no polling, no WebSocket.
Voice agents
Build production-ready voice agents with built-in turn detection and interruption handling, so you ship fast without the complexity.
Content guardrails
Redact PII and moderate content inline on audio and transcripts, so sensitive data never hits your logs or your LLM.
LLM routing
Route between every LLM from one endpoint with built-in fallback, so you swap models and survive outages without touching your code.
Scalable infrastructure
Global redundancy, enterprise-grade uptime, and 2 million hours of audio processed every day. The Voice AI infrastructure your product can depend on at any scale.
Speaker identification
Replace “Speaker A” and “Speaker B” with real names or roles, inferred from the conversation itself.
Summaries and chapters
Turn every recording into concise summaries and timestamped chapters, each with a headline and gist.
Action items
Pull the follow-ups out of any conversation, each with a timestamp and the quote it came from.
Sentiment analysis
Classify sentiment as positive, neutral, or negative, sentence by sentence, and per speaker when diarization is on.
Key phrases
Surface the words and phrases that matter most in a recording, ranked by relevance with timestamps.

Pros and cons

Pros

Industry-leading transcription accuracy with low word error rates.
Supports real-time streaming and batch transcription workflows.
Advanced features like speaker diarization, sentiment analysis, and entity detection.
Multilingual support with automatic language detection and code-switching.
Flexible, usage-based pricing with no upfront contracts and scalable infrastructure.

Cons

Pricing can be complex due to multiple add-ons and model options.
Some advanced features like custom model configurations require enterprise contact.
Primarily focused on speech-to-text; lacks built-in audio generation or editing.
May require technical expertise to fully leverage API capabilities.
Limited direct end-user interface; mainly developer-focused platform.

Developer features

Speech analysis
Go beyond basic transcription. Extract speaker ID, sentiment, chapters, and summaries from a single API call.

You?

Used AssemblyAI?

Your review helps others make better decisions. No account needed. Takes about 10 seconds.

0 questions

Frequently Asked Questions

6 things

What AssemblyAI has

For developers

Programmatic access to the product's data and features for developers.
Run the software on your own servers instead of the vendor's cloud.
A ready-made set of instructions that helps an AI agent use a product.
A Model Context Protocol server that lets AI tools connect to and act on your data.
A toolkit that lets developers build on the product using their preferred programming language.

Hosting and storage

Vendor-provided online infrastructure for deploying and running software.

12 features

Key Features

Speech-to-Text
Get clean, customizable transcripts in 99 languages with industry-leading accuracy and natural language prompting.
Real-time transcription
Stream transcripts in real time with async-level accuracy, so your agent responds fast without mishearing the user.
Synchronous transcription
Send a short clip and get a finished, flagship-accuracy transcript back in the same response — no polling, no WebSocket.
Voice agents
Build production-ready voice agents with built-in turn detection and interruption handling, so you ship fast without the complexity.
Content guardrails
Redact PII and moderate content inline on audio and transcripts, so sensitive data never hits your logs or your LLM.
LLM routing
Route between every LLM from one endpoint with built-in fallback, so you swap models and survive outages without touching your code.
Scalable infrastructure
Global redundancy, enterprise-grade uptime, and 2 million hours of audio processed every day. The Voice AI infrastructure your product can depend on at any scale.
Speaker identification
Replace “Speaker A” and “Speaker B” with real names or roles, inferred from the conversation itself.
Summaries and chapters
Turn every recording into concise summaries and timestamped chapters, each with a headline and gist.
Action items
Pull the follow-ups out of any conversation, each with a timestamp and the quote it came from.
Sentiment analysis
Classify sentiment as positive, neutral, or negative, sentence by sentence, and per speaker when diarization is on.
Key phrases
Surface the words and phrases that matter most in a recording, ranked by relevance with timestamps.

Pros and cons

Pros

Industry-leading transcription accuracy with low word error rates.
Supports real-time streaming and batch transcription workflows.
Advanced features like speaker diarization, sentiment analysis, and entity detection.
Multilingual support with automatic language detection and code-switching.
Flexible, usage-based pricing with no upfront contracts and scalable infrastructure.

Cons

Pricing can be complex due to multiple add-ons and model options.
Some advanced features like custom model configurations require enterprise contact.
Primarily focused on speech-to-text; lacks built-in audio generation or editing.
May require technical expertise to fully leverage API capabilities.
Limited direct end-user interface; mainly developer-focused platform.

Developer features

Speech analysis
Go beyond basic transcription. Extract speaker ID, sentiment, chapters, and summaries from a single API call.

You?

Used AssemblyAI?

Your review helps others make better decisions. No account needed. Takes about 10 seconds.

0 questions

AssemblyAI

Overview

What AssemblyAI has

For developers

Hosting and storage

Key Features

Speech-to-Text

Real-time transcription

Synchronous transcription

Voice agents

Content guardrails

LLM routing

Scalable infrastructure

Speaker identification

Summaries and chapters

Action items

Sentiment analysis

Key phrases

Pros and cons

Pros

Cons

Developer features

Speech analysis

Used AssemblyAI?

Frequently Asked Questions

What AssemblyAI has

For developers

Hosting and storage

Key Features

Speech-to-Text

Real-time transcription

Synchronous transcription

Voice agents

Content guardrails

LLM routing

Scalable infrastructure

Speaker identification

Summaries and chapters

Action items

Sentiment analysis

Key phrases

Pros and cons

Pros

Cons

Developer features

Speech analysis

Used AssemblyAI?

Frequently Asked Questions

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