How to Test Firefox Extensions Without Publishing: Local Development Tips

Publishing to AMO every time you want to test a change is slow and painful. Here's the full toolkit for local development.

Temporary Add-on Loading

The fastest way to load your extension:

Open Firefox and go to about:debugging

Click This Firefox in the left sidebar

Click Load Temporary Add-on...

Navigate to your extension folder and select manifest.json

The extension is loaded immediately. It disappears when Firefox restarts, but stays active during the session.

Auto-Reload on File Changes

Manually clicking "Reload" in about:debugging is tedious. Use web-ext for auto-reload:

npm install --save-dev web-ext

# Auto-reload on any file change npx web-ext run --source-dir . --watch

# Or add to package.json scripts

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{ "scripts" : { "dev" : "web-ext run --source-dir ." , "build" : "web-ext build --source-dir .…