The INIT command request is used to initiate a file upload session. It returns a media_id which should be used to execute all subsequent requests. The next step after a successful return from INIT command is the APPEND command.

See the Uploading media guide for constraints and requirements on media files.


Requests should be either multipart/form-data or application/x-www-form-urlencoded POST formats.

Note: The domain for this endpoint is upload.twitter.com


The response provides a media identifier in the media_id (64-bit integer) and media_id_string (string) fields. Use the media_id_string provided in the API response from JavaScript and other languages that cannot accurately represent a long integer.

The entire file must be uploaded before expires_after_secs seconds.

The additional_owners field enables media to be uploaded media as user A and then used to create Tweets as user B.