If you see me on this wiki, it's likely because I'm here in my capacity as a SWMT member. If you're confused why I or other users can use rollback here without permissions, it's because I have global rollback, a usergroup that shows up in Special:GlobalUsers.
This website uses the Wikivoyage API to get and display all the information you see. This is the MediaWiki API, which is a general API for accessing data from Wikimedia projects. You can find information about it here: MediaWiki API.