Timed Text Working Group
Delivering Captioning and Video Description for the Web



The mission of the Timed Text Working Group is to develop W3C Recommendations for media online captioning by developing and maintaining new versions of the Timed Text Markup Language (TTML) and WebVTT (Web Video Text Tracks) based on implementation experience and interoperability feedback, and the creation of semantic mappings between those languages.

See also the charter.


See the publication dashboard.

Test Suite

For TTML, we worked on a test suite:

For WebVTT, the test suite is part of web-platform-tests.


Meeting records

Search for minutes in the mailing list archive.

See also the previous records:

Discussion lists

Technical discussion takes place on the Working Group discussion list, public-tt@w3.org (archive). This is a public mailing list; to subscribe to the public-tt mailing list, please check the subscription procedure.

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How to join the group

This group operates under the W3C Patent Policy, which ensures that specifications published by the group can be implemented on a royalty-free (RF) basis. To record agreement from all participants with that W3C Patent Policy, joining the group involves completing several steps:

When you join, you will be added to public-tt, the publicly archived mailing-list for the group.