Custom Site JS Firefox

Custom Site JS

Run your own (per url or domain) custom JavaScript on sites.

Features & Capabilities

Have you ever wished you could customize a website to your personal preferences every time you visited it?

Ever heard of a bookmarklet? Bookmarklets run JavaScript on a page for you when you click on the bookmark. But how inconvenient to have to click a bookmark every time you visit a site?

What if you could have your JavaScript simply run on the site as the page loads with no extra effort from you? That's what this extension is about.

Custom Site JS allows you to Add, Edit, or Delete snippets of custom JavaScript, that will automatically be run on a page for you based on a URL you provide. You can create as many as you like. The only limit is a maximum of 5 megabytes as the scripts are stored in your local storage.

Everything is stored and run locally. This extension will never make any kind of external web request, network requests, or in short send any of your information anywhere. The only way it will pass any information outside of your local environment is if you create a snippet of JavaScript that explicitly sends information somewhere.

User Growth & Download Statistics

Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.
Developed by:
David Hicken
Firefox Add-ons Store
https://addons.mozilla.org/firefox/addon/custom-site-js/
Email:
cs*****@darklaser.com

User Reviews

by Br*****, 2026-06-03

by 退出*****, 2025-04-06

by 远离*****, 2025-02-24
View all user reviews ›

Is Custom Site JS Safe?

Risk impact
Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

Custom Site JS requires some sensitive permissions that could impact your browser and data security. Exercise caution before installing.

Risk impact analysis details
  • Critical Grants access to browser tabs, which can be used to track user browsing habits and history, presenting a privacy concern.
  • Critical ****** ****** ** *** ********* ****** * *********** ******** **** ** ** *** ******* *** ****** **** **** *** ******* *****
  • High ****** ********* ** * ****** ******** ******** ********** * ******* ******* *****
Risk likelihood
Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

Custom Site JS has earned a fairly good reputation and likely can be trusted.

Risk likelihood analysis details
  • High This extension has low user count. Unpopular extensions may not be stable or safe.
  • Low **** ********* *** ******* **** **** * ****** **** ***** ******** *** **** ****** ** ** ****** *** *****
  • Low **** ********* *** ***** **** **** * ****** **** ***** ********** *** **** ****** ** ** ****** *** *****
  • Good **** ********* *** **** **** *******
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