GreaseMonkey is a tool that lets you run special scripts in the Firefox web browser that change the way web sites behave. For instance you can install a script that adds download links to YouTube videos, or a script that changes links in a Google Image search so that you can go straight to the original photo when you click on an image.
A number of other browsers also support userscripts, including the desktop version of Google’s Chrome browser. But the native Android browser does not. Enter TamperMonkey. This free app for Android lets you install and run userscripts on your mobile device. TamperMonkey also works with Google Chrome, offering some GreaseMonkey features that are absent from the browser’s native script support.
TamperMonkey for Android is basically a standalone and very simple web browser that lets you install and manage scripts. Not all of them work properly on a mobile device — but that’s largely because when you visit many web pages in a mobile web browser you don’t see the full desktop version of the page which the scripts are designed to work with.
The app is available as a free download. It’s in beta and feels a bit rough around the edges. But if you’ve been looking for a way to run userscripts on your phone, you might want to give it a try.