Chrome retired Manifest V2, and Cookie AutoDelete — the extension a lot of privacy-minded people leaned on to wipe cookies automatically — stopped working with it. CookieMop does the same job under the new extension rules.
It records which sites each tab visits. Close the last tab for a site and a 15-second timer starts; when it fires, that site's cookies are deleted. The delay is adjustable from 0 to 60 seconds, so closing a tab by mistake costs you nothing.
Whitelisted sites are never touched, which is how Gmail and your bank stay logged in. Greylisted sites survive until the browser closes. You can also widen the sweep from cookies alone to localStorage, IndexedDB, CacheStorage and Service Workers.
Moving over from the old extension is one step: export its expressions as JSON, load the file in the options page, and the whitelist and greylist come with you.
Under the hood it is 1,807 lines of plain JavaScript, no runtime dependencies, no build step, and 21 automated browser tests. The extension makes zero network requests, which for a tool that can read every cookie you own is the only design worth trusting.
One gap, stated plainly: partitioned (CHIPS) cookies set by third-party embeds are left alone, because the extension cookies API cannot list them per site.