User JavaScript and CSS

4.8 (

652 ratings

)

Extension Developer Tools 200,000 users

187 support issues

Eduardo Silveira Rios

Feb 6, 2026

All rules are gone

Hey, I got my list of rules emptied, the list has 0 rules. Where the rules are saved by default? Is there a folder on my computer where I can check or a cloud access to login/verify? I suspect that it was caused by a plugin update, I never updated it. The plugin functionality broke because of high memory usage on Chrome, I went to Extensions clicked Repair, them the list is gone. More details: I always used a Light interface, and now I have a dark one. I never configured the "Theme" option in the extension Settings, so I suppose I was using a version that "Light" was the default theme (instead of dark). Can I somehow download an old version of the extension (the latest that had a light theme by default) intending to recover the lists?

Francis Vanderbruggen

Sep 16, 2025

Icon indication of triggered script or CSS

Hi, it would be nice to see an indication on the extension icon in the toolbar of chrome, when a injection is active on the current page. Would this be feasible? :-)

Борис Фанюк

Aug 26, 2025

Order of rules

I have several scripts on the same page (to split huge amount of code).
However, I would like some scripts to be loaded in specific order.Is there a possibility for this?
Thanks!

Michael Garcia

Jul 24, 2025

Remote update // version control

Hello, is there a way to have the code sync with a git repo so the script / style can be managed with version control and other IDE development support without copy/pasting the code at each iteration?

으하핫

Jul 8, 2025

After the July 7th update, the browser called Whale is no longer usable. Developer mode is

After the July 7th update, the browser called Whale is no longer usable. Developer mode is turned on, but it keeps telling me to turn it on repeatedly.

Abhishek Junghare

Jul 7, 2025

Global styles aren't getting removed

CSS styles added into *://*/* URL are not getting removed. I tried -

1. Clearing all styles inside that URL
2. Removing that URL itself

But, the styles are still getting added. Only option is to remove extension entirely, with clearing its data, and then re-installing.

Andrew

Jul 1, 2025

Гитхаб

Когда расширение появиться на гитхабе?

Marynaty Guzman

Jun 13, 2025

Activar javascript

No puedo activar javascript y no me permite usar Google si no lo activo

Jose Rebollo

Jun 2, 2025

No puedo instalar

Me aparece el siguiente mensaje de error:

Error de descarga: No se ha podido cargar la secuencia de comandos en segundo plano "src/background.js".

Hodaka Hashi

May 13, 2025

Deleted CSS/JS still outputting to page

I love your extension and use it daily to test changes locally, add functionality and changing styling of sites I use etc... I've been experiencing a problem from time to time however, and wanted to see if you have any suggestions.

As mentioned above, I often use the extension to test new changes we need to make to a website. Once I'm done with testing, I delete the rule, but have found that the CSS/JS is sometimes still injected into the page.

Not sure if it matters, but this happens with devtools open with caching disabled.

The rule isn't appearing on the popup, nor on the options page. Do you have any suggestions? I assume I can export rules > reinstall extension > import rules, but unsure this would solve the issue in the long run?

Thanks!