Tampermonkey

Tampermonkey is a Google Chrome browser extension that allows you to write and install user scripts that enhance the functionality of your browser or of webpages you regularly visit.
Though the browser already supports user scripts, Tampermonkey allows you to add and interact in a new way with them. It offers you an easier way of installing, customizing and managing the scripts.
The extension can be added from the Chrome web store or, if you have the CRX file laying around you can simply drop it onto the browser’s main window to install it. Once installed, it adds a new icon to the browser’s interface from where you can easily access it in order to add scripts or disable them.
Tampermonkey offers you the use of an intuitive dashboard from where you can add new user scripts, organize them, change extension settings and even export them to your computer. If you have the necessary experience to do so, you can write your own scripts using the built-in editor. If offers you a simple text editor with basic functions such as ‘Search’, ‘Replace’, ‘Jump to line’ and ‘Insert constructor’.
From the same editor, you are able to save the script to your hard drive, reset it or run a syntax check. A feature that Tampermonkey brings and uses to its advantage is ‘Automatic Script Update’. If the script was added from a website that offers this kind of content, you can set the application to check at regular intervals for new versions of the script.
Depending on your experience with user scripts, Tampermonkey allows you to switch between three different types of configuration. Each of the ‘Novice’, ‘Beginner’ and ‘Advanced’ modes offer you a certain number of features that extend its usability.
In closing, if you want to add custom or predefined user scripts to your Chrome browser, then you can certainly use Tampermonkey.