Witchcraft: JS/CSS injector

Witchcraft: JS/CSS injector

Witchcraft loads custom Javascript and CSS directly from a folder in your file system. Think GreaseMonkey for developers.

Witchcraft: JS/CSS injector
What is Witchcraft: JS/CSS injector?
Witchcraft: JS/CSS Injector is a Google Chrome extension designed for developers. It allows the loading and injecting of custom Javascript and CSS directly from their file system into the pages that match their file names. It supports automatic updates of scripts after editing, is cross-platform and can handle both JS and CSS. It enhances the functionality of standard scripting tools for a more streamlined development process.
Users: 1,000+
Rating: 4.60 (10)
Version: 2.6.1 (Last updated: 2020-03-10)
Creation date: 2020-03-10
Risk impact: Low risk impact
Risk likelihood: Low risk likelihood
Manifest version: 2
Size: 27.89K
URLs: Website
Stats date:

Other platforms

Not available on Firefox
Not available on Edge
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Think Greasemonkey for developers.

Witchcraft is a Google Chrome extension for loading custom Javascript and CSS directly from a folder in your file system, injecting them into pages that match their files names.

It works by matching every page domain against script file names available in the scripts folder. For instance, if one navigates to https://www.google.com, Witchcraft will try to load and run google.com.js and google.com.css.

Witchcraft also tries all domain levels. For instance, if one accesses https://gist.github.com, it will try to load, in this order: com.js, github.com.js and gist.github.com.js... and the same for CSS. All domain levels for which a script is found will be loaded, not just the first one.

Whenever you edit or create new scripts, there's no need to reload anything other than the page where the scripts are supposed to run. This is what makes Witchcraft special and different than other popular scripting tools, like Greasemonkey or Tampermonkey.

Since Witchcraft runs as a Chrome extension, it is also cross-platform. It has been tested on Windows, MacOS and Linux.


  • scripts are automatically updated after you edit them - no need to reload anything;
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User reviews
User reviews summary
These summaries are automatically generated weekly using AI based on recent user reviews. Chrome Web Store does not verify user reviews, so some user reviews may be inaccurate, spammy, or outdated.
  • Better than Tampermonkey
  • Great for customizing webpages
  • Positive impact on visually-impaired users
  • Feature to apply JS/CSS
  • Developer responsiveness about feature requests
  • Difficulty in setting up
  • No response from developer
  • Not working in Chrome OS
  • Lack of Firefox port
Most mentioned
  • Tampermonkey
  • Lucio (Developer)
  • Customizing webpages
  • Chrome OS
  • Feature requests
Recent reviews
I had trouble setting it up. I followed the instructions as best I could and then reached out to the developer with a descriptive inquiry, inclusive of images. No response. Nonetheless, I can't knock the app too much because of my technical limitations. If I could get it to work it would be significantly better than tampermonkey.
by Matt Matt, 2022-05-23

I can't believe I was using Tampermonkey for so long as this is clearly better by a longshot.
by Jason McElwaine Jason McElwaine, 2021-08-01

Love this one!
by E H E H, 2020-03-01
View all user reviews
Risk impact

Witchcraft: JS/CSS injector is relatively safe to use as it requires very minimum permissions.

Risk likelihood

Witchcraft: JS/CSS injector has earned a fairly good reputation and likely can be trusted.

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Promo images
Witchcraft: JS/CSS injector small promo image
Small promo image
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