Web System Injection (WSI) is a Chrome extension designed to enhance existing websites by allowing users to inject custom functionalities at the domain level. This free tool provides a user-friendly interface for importing plugins from ZIP files, which automatically inject scripts and CSS into the targeted domain when accessed. Users can easily manage their plugins by enabling, disabling, or deleting them as needed.

The extension also includes a plugin SDK that allows developers to add buttons, panels, and storage options, making it a versatile tool for personal browser customization. To use WSI, simply click the WSI icon in the toolbar, import a plugin ZIP file, and navigate to the desired domain to see the plugin in action. This tool serves as a personal customization solution for developers looking to enhance their web browsing experience.