Permissions explained

When you install Crumble, Chrome shows two warnings: "Read and change all your data on all websites" and "Display notifications". Here is why.

Permission	What Crumble uses it for
Access to all websites	Chrome only lets an extension read and delete the cookies of sites it has access to. To clean any site you leave, Crumble needs access to all of them. The same access lets it see which sites your tabs are on, so it knows what is still open. It never reads or changes page content, injects nothing into pages, and doesn't ask for your history.
Cookies	Read and delete cookies, including third-party and partitioned ones, and restore them when you click Undo.
Browsing data	Clear LocalStorage, IndexedDB, Cache Storage and Service Workers for sites you've left.
Storage	Save your rules, settings and cleanup log in your browser.
Alarms	Run a scheduled cleanup on time even after Chrome pauses the extension in the background.
Notifications	Show a short message after a cleanup, if you turn that on.
Context menus	Add "Keep this site" and similar entries to the right-click menu, if you turn that on.

The source code is public, so anyone can check that Crumble does only this: github.com/rahulcv1003/crumble-cookie-cleaner.