AssemblyAI Release Notes

Universal-3-Pro release

We've released Universal-3-Pro, our most powerful Voice AI model yet—designed to give you LLM-style control over transcription output for the first time.
Unlike traditional ASR models that limit you to basic keyterm prompting or fixed output styles, Universal-3-Pro lets you progressively layer instructions to steer transcription behavior. Need verbatim output with filler words? Medical terminology with accurate dosages? Speaker labels by role? Code-switching between English and Spanish? You can design one robust prompt and apply it consistently across thousands of calls, getting workflow-ready outputs instead of brittle workarounds.
Out of the box, Universal-3-Pro outperforms all ASR models on accuracy, especially for entities and rare words. But the real power is in the prompting: natural language prompts up to 1,500 words for context and style, keyterms prompting for up to 1,000 specialized terms, built-in code switching across 6 languages, verbatim transcription controls for disfluencies and stutters, and audio tags for non-speech events like laughter, music, and beeps.

How to use it:

• Set "speech_models": ["universal-3-pro", "universal"] with "language_detection": true for automatic routing and 99-language coverage
• Use prompt for natural language instructions and keyterms_prompt for boosting rare words (up to 1,000 terms, 6 words each)
• Available now via the /v2/transcript endpoint
• Read the full documentation

Universal-3-Pro represents a fundamental shift in what's possible with speech-to-text: true controllability that rivals human transcription quality, with the consistency and scale of an API.
Try Universal-3-Pro →

Streaming endpoints overview

We've launched new streaming endpoints that give you control over latency optimization and data residency. Choose the endpoint that best fits your application's requirements—whether that's achieving the lowest possible latency or ensuring your audio data stays within a specific geographic region.

Edge Routing (streaming.edge.assemblyai.com)

automatically routes requests to the nearest available region, minimizing latency for real-time transcription. With infrastructure in Oregon, Virginia, and Ireland, this endpoint delivers our best-in-class streaming performance regardless of where your users are located.

Data Zone Routing (streaming.us.assemblyai.com and streaming.eu.assemblyai.com)

guarantees your data never leaves the specified region. This is designed for organizations with strict data residency and governance requirements—your audio and transcription data will remain entirely within the US or EU, respectively.

How to use it:

• wss://streaming.edge.assemblyai.com/v3/ws — Lowest latency
• wss://streaming.us.assemblyai.com/v3/ws — US data residency
• wss://streaming.eu.assemblyai.com/v3/ws — EU data residency

The default endpoint (streaming.assemblyai.com) remains unchanged.

Multichannel speaker diarization with pre-recorded transcription

We've added support for multichannel speaker diarization with pre-recorded transcription, allowing you to identify individual speakers across multiple audio channels in a single API request. This unlocks accurate transcription for complex audio scenarios like hybrid meetings, call center recordings with supervisor monitoring, or podcast recordings with multiple mics. Speaker labels are formatted as 1A, 1B, 2A, 2B, where the first digit indicates the channel and the letter identifies unique speakers within that channel. For example, in a meeting where Channel 1 captures an in-room conversation between two people and Channel 2 captures a remote participant, you'll get clear attribution for all three speakers even though Channel 1 contains multiple talkers.

How to use it

• Set both multichannel=true and speaker_labels=true in your transcription request—no other changes needed
• Available now for all Universal customers across all plan tiers
• View documentation

Universal delivers industry-leading accuracy with advanced features like multichannel support and speaker diarization, giving you the precision and flexibility needed to build production-grade voice AI applications.

We've added support for multichannel speaker diarization with pre-recorded transcription, allowing you to identify individual speakers across multiple audio channels in a single API request.

This unlocks accurate transcription for complex audio scenarios like hybrid meetings, call center recordings with supervisor monitoring, or podcast recordings with multiple mics. Speaker labels are formatted as 1A, 1B, 2A, 2B, where the first digit indicates the channel and the letter identifies unique speakers within that channel. For example, in a meeting where Channel 1 captures an in-room conversation between two people and Channel 2 captures a remote participant, you'll get clear attribution for all three speakers even though Channel 1 contains multiple talkers.

How to use it

• Set both multichannel=true and speaker_labels=true in your transcription request—no other changes needed
• Available now for all Universal customers across all plan tiers
• View documentation

Universal delivers industry-leading accuracy with advanced features like multichannel support and speaker diarization, giving you the precision and flexibility needed to build production-grade voice AI applications.‍

Release notes

We've updated how uploaded audio files are deleted when you delete a transcript, giving you immediate control over your data.

Previously, when you made a DELETE request to remove a transcript, the associated uploaded file would remain in storage for up to 24 hours before automatic deletion. Now, uploaded files are immediately deleted alongside the transcript when you make a DELETE request, ensuring your data is removed from our systems right away.

This change applies specifically to files uploaded via the /upload endpoint. If you're reusing upload URLs across multiple transcription requests, note that deleting one transcript will now immediately invalidate that upload URL for any subsequent requests.

How it works

• When you send a DELETE request to remove a transcript, any file uploaded via /upload and associated with that transcript is now deleted immediately
• This applies to all customers using the /upload endpoint across all plans
• If you need to transcribe the same file multiple times, upload it separately for each request or retain the original file on your end

AssemblyAI's APIs are built with security and data privacy as core principles. Our speech-to-text and audio intelligence models process your data with enterprise-grade security, and now with even more granular control over data retention.

Learn more about our data security practices

Google's newest Gemini 3 Flash Preview model is live in the LLM Gateway.

This model delivers faster inference speeds with improved reasoning capabilities compared to previous Flash versions. Gemini 3 Flash Preview excels at high-throughput applications requiring quick response times—like real-time customer support agents, content moderation, and rapid document processing—while maintaining strong accuracy on complex queries that would have required slower, more expensive models.

For more information, check out our docs here.

We've updated how uploaded audio files are deleted when you delete a transcript, giving you immediate control over your data.

Previously, when you made a DELETE request to remove a transcript, the associated uploaded file would remain in storage for up to 24 hours before automatic deletion. Now, uploaded files are immediately deleted alongside the transcript when you make a DELETE request, ensuring your data is removed from our systems right away.

This change applies specifically to files uploaded via the /upload endpoint. If you're reusing upload URLs across multiple transcription requests, note that deleting one transcript will now immediately invalidate that upload URL for any subsequent requests.

How it works

• When you send a DELETE request to remove a transcript, any file uploaded via /upload and associated with that transcript is now deleted immediately
• This applies to all customers using the /upload endpoint across all plans
• If you need to transcribe the same file multiple times, upload it separately for each request or retain the original file on your end

AssemblyAI's APIs are built with security and data privacy as core principles. Our speech-to-text and audio intelligence models process your data with enterprise-grade security, and now with even more granular control over data retention.

Learn more about our data security practices
‍