Witchcraft is a Google Chrome extension that allows developers to load custom Javascript and CSS directly from a folder in their file system. It functions similarly to Greasemonkey, but with the added benefit of automatically updating scripts without the need to reload anything other than the page where the scripts are supposed to run.

Witchcraft is cross-platform and has been tested on Windows, MacOS, and Linux. It supports both JS and CSS, and offers features such as the ability to load other JS/CSS files from inside your domain scripts using the `@include` directive, as well as the option to use custom server addresses, including remote ones.

For more information, please visit the developer's website.