File with .CRX extension contains Google Chrome web browser addon or theme saved as ZIP archive with modified file header. CRX container can store executable files, images, JS scripts or JSON objects. This file format is in most cases not recognized by standard decompression utilities, and as such requires dedicated software to extract it, for example crxextractor tool.

Chrome extensions can be installed manually by dragging CRX files to the ‘Extensions’ window. You can open this window by choosing ‘Window’ -> ‘Extensions’ from the application menu, or by setting browser address to chrome://chrome/extensions/. CRX files are used for installing browser addons such as browser games, ad-blockers, and news readers. Installing extensions via Chrome Web Store is the standard method of installing addons – browser automatically downloads the extension, unpacks the file, installs it, and finally removes the CRX file.