Greetings, REST API consumers!

We recently marked duplicate transform endpoints as deprecated in the MediaWiki REST API. The deprecated endpoints reflect a trailing slash at the end of the path, and are duplicative of comparable endpoints without the trailing slash. Developers who are calling these endpoints are advised to remove the trailing slash from the path their requests. *We plan to remove the trailing slash endpoints by the end of January 2026*.

*== What should I call instead? ==* Identical endpoints already exist; simply remove the trailing slash from your requests and the calls will go through. Users can review documentation and execute test calls for both versions of the transform endpoints using the new REST Sandbox https://www.mediawiki.org/wiki/Special:RestSandbox (Special:RestSandbox), as seen below: [image: image.png]

*== Why are we deprecating and removing these endpoints? ==* These endpoints contain a trailing slash in the path, which is confusing for consumers and goes against REST routing paradigms. The trailing slash was added erroneously within the MediaWiki Core APIs and resulted in duplicate routes when combined with endpoint migration for the RESTBase Sunsetting project. Few users have adopted the trailing slash version, which is motivating us to move quickly on its removal, before more tools, bots, and developers are impacted.

*== Will this result in a major version change for the MediaWiki REST API? ==* No. Although this is technically a breaking change, we plan to remove the endpoints without incrementing the major version across the board. In this case, we decided to proceed with removal without a version increment due to the limited adoption of these specific endpoints, and to minimize disruption across our developer community as a major version change may have more cascading impacts.

*== Where can I get more information about the deprecation process? ==* For more information about our approach to deprecation overall, see the new API Deprecation https://www.mediawiki.org/wiki/API/Deprecation page for more information about deprecation processes.

If you have any questions, comments, or concerns, please feel free to raise them here, or join the discussion on the new API Deprecation talk page https://www.mediawiki.org/w/index.php?title=Talk:API/Deprecation.

Thanks, Halley *Halley Coplin* (she/her) Sr. Product Manager, MediaWiki Interfaces Wikimedia Foundation https://wikimediafoundation.org/