For AI agents: a documentation index is available at /llms.txt. Markdown versions of all pages can be requested by appending `.md` to the URL, or by setting the `Accept` header to `text/markdown`.
Skip to main content
Speech to TextRealtime transcription

Limits – Realtime

Learn about the limits for the Speechmatics Realtime API

Speechmatics limits the number of concurrent Realtime sessions by account type. The current limits are listed in the table below:

Max. concurrent sessions
Free2
Pro50
EnterpriseCustom

Please reach out to Support if you need to increase the above limits.

Session limits​

Realtime SaaS sessions will be automatically ended if any of the following criteria are met:

  • Session duration reaches 48 hours
  • No audio data (AddAudio messages) sent for 1 hour
  • No audio or ping/pongs sent for 3 minutes.

When a session is automatically ended, the Realtime SaaS service will send an in-band error followed by a closing handshake with code 1008. For more information, see the Realtime API Reference.

Guidance for users​

Clients can disconnect a session before it is automatically terminated and immediately reconnect a new session. Note that new sessions will typically start in less than a second. If seamless transition is required, the new session can be connected a few seconds before disconnecting the old session.

Since unpredictable network issues can cause WebSocket connections to be dropped, we recommend graceful handling of session termination for long-running sessions.

Custom dictionary limits​

If a session's custom dictionary (additional_vocab) contains more than 20,000 items, the Realtime SaaS service sends an in-band error message of type protocol_error and closes the WebSocket connection with code 1003. See Custom dictionary content limits for details.

Data retention limits​

Speechmatics Realtime SaaS does not store audio files, transcripts, or configuration data.