My Pwd Tool by Thibault Ducray

This extension is a companion to the MyPwdTool desktop app (macOS & Windows) — a free, end-to-end encrypted password manager with no account and no cloud storage of your data. It requires the MyPwdTool app to be installed and running; it does not work on its own.

WHAT IT DOES
• Fills matching username/password entries into login forms on the site you're visiting
• Offers to save a new password, or update an existing one, after you submit a login/signup form
• Shows a lock/unlock icon reflecting your vault's current state

HOW IT TALKS TO YOUR VAULT
The extension never has direct access to your vault or your master password. It communicates exclusively with the MyPwdTool app running on the same computer, over Firefox's native-messaging mechanism — a local, one-to-one channel with no network component. The first time it connects, MyPwdTool shows a one-time approval dialog you must accept yourself.

WHAT IT COLLECTS
Nothing. No analytics, no tracking, no data sent anywhere by the extension itself. The only network traffic your vault ever generates (if you turn on the optional paid sync feature) goes through the main app, end-to-end encrypted, never through this extension.

Full details: https://mypwdtool.com/browser-extensions/