Dungeon Party is a single-player browser game. By default it stores everything locally in your browser and sends nothing about your progress anywhere. Cloud save is entirely optional.
Nothing about your account or progress leaves your device. You can back up or move your save yourself with the export code / file in Options → Save & Load.
Signing in is optional and only enables saving your progress to the cloud so it follows you across devices. When you sign in:
On Cloudflare infrastructure (a Cloudflare Worker + D1 database) tied to the game's domain. A session cookie (dp_session, HttpOnly) keeps you signed in.
In Options → Account & Cloud Save: Sign out stops syncing (your local save stays on the device), and Delete account & data permanently removes your stored profile and cloud save from the server.
The live site uses self-hosted, cookieless Umami analytics — aggregate play stats only, no personal profiles.