If you support or are planning to support x-callback-url, please let us know at info _at_  x-callback-url _dot_ com, or @xcallbackurl.

Apps with x-callback-url interfaces (links to API documentation)

Know of an app supporting x-callback-url not list here? Please let us know!

Phillip Gruneich has also been maintaining a great great list of apps with callback support.

A directory of apps supporting x-callback-url is maintained at, and excellent resource for finding out about all sorts of great URL actions available on iOS.

Visit x-callback-url app directory.