Curious what an extension is actually doing before you install it, or want to learn how a well-built one works? You can view almost any Chrome extension’s source code without writing anything yourself.
How to Download and Unpack an Extension
- Find the extension’s ID in its Chrome Web Store URL, the long string of letters after its name.
- Use a CRX downloader site to save the extension’s .crx file.
- Rename the file extension from .crx to .zip.
- Extract the zip file like any other archive to see all the extension’s code, including its manifest.json file.
How to View an Installed Extension’s Files Directly
- Go to chrome://extensions.
- Turn on Developer mode in the top right corner.
- Click Details on the extension, then note the ID shown.
- Navigate to your Chrome profile’s Extensions folder and open the folder matching that ID to browse its files.
Quick Tips
- Reading the manifest.json file first tells you what permissions the extension actually requests, which is often the fastest way to spot something suspicious.
- Many open-source extensions also publish their code on GitHub, so check there before digging through files manually.
Now you can look under the hood of any Chrome extension, whether you’re checking it’s safe or just curious how it was built.
