Anti-Blur
What it does#
Stops a site from knowing you looked away.
Switch tabs, click into another app, or move the mouse off the page, and most sites can tell. They use it to pause the video, stop the timer, dim the page, throw up an "are you still watching?", or simply record how long your attention was elsewhere. Anti-Blur makes the page believe it is focused and visible the whole time.
"Blur" is the browser's word, not the camera's. A blur event is what a page receives when it loses focus. Nothing here sharpens an image.
What that looks like in practice#
- Videos keep playing when you switch tabs.
- Nothing dims, pauses or asks whether you are still there.
- Attention analytics get a flat line.
- A focused text box is not told it lost focus when you click into another window, and is not told it got focus back when you return.
In a background tab Chrome itself slows a page's timers to about once a second, and after five minutes to about once a minute. Anti-Blur keeps the page from knowing that it is in the background, and keeps its animation loop stepping at that pace instead of stopping — but it cannot lift the limit. A window you merely clicked away from is not slowed at all.
What it is not for
This page used to list "exam and training pages stop logging that you left" as a feature, which is a use the Terms prohibit — defeating proctoring, or a training record someone relies on, is the one thing Anti-Blur is not sold for. Advertising it and forbidding it at the same time is not a position, so the line is gone.
What it cannot do#
- It cannot stop a site that measures something else — a page that watches request timing or frame rate can still infer a great deal.
- It does not block ads or trackers. That is Sodium.
- It does not stop a site recording your screen. That is Perch.
- It cannot make a background tab run at full speed (above).
- A page that asks whether its own text box still matches
:focuscan still tell the window lost focus.
Turning it off for one site#
Click the Anti-Blur icon and use the switch next to the site's name. It says Anti Blur off for this site or Anti Blur on for this site, and the toolbar icon shows OFF on that site's tabs while it is off.
The change applies from the next load, so the popup offers a Reload button. Anti-Blur is either in a page from its very first line or not at all; it cannot be taken back out of a page that already has it.
Alt+Shift+B does the same for the tab you are on, and reloads it. Change the key in chrome://extensions/shortcuts.
"This site" is the name in the address bar: turning it off for www.youtube.com leaves music.youtube.com alone. The list stays in your browser and is never sent anywhere — see the privacy policy.
Its own terms and privacy policy#
Anti-Blur carries its own two documents rather than sitting under the site-wide ones: Terms of Use and Privacy Policy. Everything else on this site is governed by the Terms and Privacy linked at the bottom of every page.
What it can see#
Nothing. Anti-Blur asks for no permissions at all: no storage, no network access, no service worker, no third-party code. It is a single script that runs before the page's own scripts and changes what four browser properties report.