CUSTODIAN
How it works
The mechanism, not the pitch.
Custodian keeps an eye on your open tabs. When you close the last tab for a site, it waits a few seconds in case that was an accident, then clears that site's cookies, storage, and cache, and resets whatever permissions it had. This page covers the actual sequence, what's checked before anything happens, and where the honest limits are.
What happens when you close a tab
You close the last tab for a site
Custodian tracks open tabs by origin. If you still have another tab open for the same site, nothing happens: the countdown only starts once no tab for that origin remains open.
The grace period starts
A short countdown begins, five seconds by default and configurable from 0 to 60. It's cancelable the entire time: reopen the site, or cancel it from the popup, and the countdown stops with nothing cleared.
The grace period runs out
If nothing reopens the site before time is up, Custodian moves ahead. This is the only trigger. There's no polling timer running in the background and no periodic sweep, just this one event per site.
Custodian checks what it's about to touch
Before resetting any permission, Custodian checks whether that permission was actually customized for the site. Camera access you never granted isn't "reset" to anything, because there's nothing to reset. Only permissions that differ from Chrome's default get touched.
Custodian clears the site and writes a receipt
Cookies, storage, and cache for that origin are cleared, verified permissions are reset, and a receipt is written: exactly what was cleared, exactly what was reset, timestamped. It's reviewable any time from the popup or the full activity log.
What gets cleared
Everything a site could use to remember you.
This is per-origin, not global: closing the last tab for one site never touches data belonging to any other site, including ones you still have open.
Permission resets
Verified, not automatic.
Chrome lets a site ask for camera, microphone, location, notifications, clipboard, automatic downloads, sound, and pop-up permissions. Any of those you've granted or blocked for a site stick around long after you're done with it.
Custodian doesn't reset permissions blindly. Before touching anything, it checks which permissions were actually customized for that specific site, comparing the current state against Chrome's default. A site you never gave camera access to was never granted an override in the first place, so there's nothing for Custodian to reset, and its receipt reflects that: only permissions that actually changed show up as reset.
The permission-override fix
Chrome gives you one way to undo an override: undo it for everyone.
This is the part of Custodian we're most proud of, because the platform genuinely doesn't offer a clean way to do it.
An extension can override a site's permission, which is how Custodian resets one after you're done with a site. But Chrome gives an extension no API to delete that single override later. The only tool available clears an extension's overrides for an entire permission type, across every site at once. Left alone, that creates a real problem: once Custodian resets, say, a camera permission for one site, its override for that permission type is what's technically in effect. If you revisit the site and click Allow again, the old override can still outrank your new click, and the site keeps re-prompting as if nothing changed.
Custodian's fix: it keeps its own record of exactly which sites it's touched, per permission type. When you whitelist a site, or run "Fix stuck permissions" directly, Custodian clears every override for that permission type, then immediately writes every other affected site's protection straight back from its own record. The net effect looks selective, one site freed, everyone else undisturbed, even though it's built from two tools that are only ever blunt on their own.
The practical difference: whitelisting a site, or using "Fix stuck permissions," now undoes past resets, not just prevents future ones. If a site has been stuck re-prompting, this is what fixes it.
Network isolation
Isolate this tab: a real block, with a real edge.
"Isolate this tab" is a per-tab, on-demand toggle. Turn it on for a tab and Custodian blocks that tab's outgoing navigations, fetch and XHR requests, scripts, images, and WebSocket connections, using Chrome's declarativeNetRequest API scoped to that tab's ID. It doesn't touch any other tab, and it doesn't undo anything the tab already loaded before you turned it on.
The honest limit
This is not full air-gapping. It does not block WebRTC. WebRTC negotiates its own peer-to-peer channel outside the request pipeline this feature hooks into, so a tab using WebRTC can still establish a connection while isolated. If you need to be certain nothing leaves a tab, isolation alone isn't sufficient for that.
Whitelist, Greylist, Shield Mode
Three ways to tell Custodian to back off.
Whitelist
Mark a site never-touch. Custodian won't clear its data or reset its permissions until you remove it from the list yourself. Permanent by default.
Greylist
Mark a site skip-for-now. It behaves like a temporary whitelist entry that expires on its own, 24 hours by default, configurable to whatever window makes sense for you.
Shield Mode
A single toggle that flips Custodian's default entirely. Normal mode clears everything except your whitelist. Shield Mode clears nothing except sites you've explicitly marked clean, for people who'd rather opt in than opt out.
Shield Mode
Off: Custodian clears everything except your whitelist.
Frequency-based suggestions
A quiet nudge, never an automatic action.
Custodian uses plain pattern matching, no model, nothing sent anywhere, to notice when you visit a login-shaped site often enough that clearing it every time is probably more friction than protection. When that happens, it offers, once, to whitelist the site. You can dismiss it, and it won't ask again for that site. Custodian never whitelists anything on its own.