KTDash is a web-based app (PWA) built in AngularJS (front end) and PHP + MySQL (back end) to help KillTeam players build their rosters and play their games.
This is out of date and will be archived/deleted eventually. Instead, look at new new ktdashv4 rewrite.
The front end is built on AngularJS, with some server-side code to improve first page load time and crawler indexing.
The back end is built in PHP using a MySQL database to store all team, user, and roster information.
If you want to build your own front end, it will need to talk to the back end API to get team information, log users in, and manage user rosters and operatives.
The API is not currently documented, but that documentation effort is in progress.