Password Filler

THIS EXTENSION REQUIRES THE PASSWORD FILLER MACOS DESKTOP APPLICATION. It is a thin proxy that has no functionality on its own. macOS only.

Get the Mac app: https://github.com/andreasisaak/password-filler/releases/latest

How it works

When a website returns 401 + WWW-Authenticate: Basic, the extension asks the locally-installed Password Filler Mac app for matching credentials and fills the dialog before the browser shows it. If the Mac app isn't running, the native browser dialog appears as usual.

Requirements

• macOS 14 (Sonoma) or newer
• 1Password 8 desktop app, signed in
• 1Password Settings → Developer → "Integrate with 1Password CLI" enabled
• Password Filler Mac app installed (free, open source)

• webRequest + webRequestAuthProvider — detect 401 challenges and supply credentials so the dialog fills silently.
• nativeMessaging — talk to the local Mac app over Firefox's Native Messaging channel; never to any remote server.
• alarms — keep the background script alive between auth challenges so the Native Messaging port stays connected.
• host permissions on all URLs — HTTP Basic Auth can occur on any URL; the extension reads only the hostname of 401 responses, never page content, cookies, headers, or form data.
• scripting — inject a one-time confirmation banner into the page after a successful credential fill, so users can see at-a-glance which sites are HTTP-Basic-Auth-protected (otherwise the silent fill makes it invisible).
• storage — remember which origins have already shown that confirmation banner, so it appears only on your first visit per site. No credentials, no browsing history.

All credential lookups happen entirely on your device. No data is sent to any external server. Passwords are never written to disk by the extension; they live in your local 1Password vault and are encrypted at rest by the Mac app.

Open source

Source code, issue tracker, and Mac app downloads: https://github.com/andreasisaak/password-filler