Redmine

To have Redmine be able to at least use POST method with web hooks upon multiple events, similarly implemented in GitLab or GitHub. This will allow to integrate Redmine into other networks, which people may use for team communication.

• On Issue Created
• On New Repository Commit
• On Forum Post
• On Wiki page edit
• On Wiki page created
• On New Document added
• On New activity
• On News posted

etc

To make it better than GitLab, you can even allow users to input custom JSON subscribe headers and subscribe body in order to make it compatible with any web hook format, else some services might have parsing problems and result in a rejected request.