Steps to Edit an .XPI (Firefox Add-on) File
1. Extract the .XPI File
- Download the .xpi file.
- Rename it from
.xpito.zip(e.g.,addon.xpi → addon.zip). - Extract the
.zipfile using WinRAR, 7-Zip, or any unzip tool.
2. Modify the Add-on Files
- Inside the extracted folder, you'll find JavaScript (.js), manifest.json, and HTML/CSS files that define the extension’s functions.
- Edit the JavaScript or other files as needed using Notepad++, VS Code, or any text editor.
3. Repack the Add-on as .XPI
- After making changes, compress the folder back into a ZIP file.
- Rename it from
.zipto.xpi(e.g.,addon.zip → addon.xpi).
4. Install the Modified Add-on in Firefox
- Open Firefox and type
about:debuggingin the address bar. - Click "This Firefox" → "Load Temporary Add-on."
- Select your modified .xpi file to test it.
⚠️ Note: If the extension is signed, you cannot use the modified version unless you disable Firefox’s "Extension Signature Requirement" in about:config.

