Checker for Fastmail

A lightning-fast, lightweight Chrome Extension for Fastmail users. Check and preview unread Fastmail emails directly from your browser toolbar via a secure two-pane layout without opening a new tab.

Note

Disclaimer: Checker for Fastmail is an independent open-source project and is not affiliated with, sponsored by, or endorsed by Fastmail Pty Ltd. Fastmail is a registered trademark of Fastmail Pty Ltd.

Built with Svelte 5, Vite, and TypeScript, running on Chrome Manifest V3 (MV3). It uses Fastmail's standard JMAP API (RFC 8620 / RFC 8621) and securely stores a Fastmail API Token locally in the browser.

Features

• Blazing Fast & Lightweight: Opens instantly with zero bloat, communicating directly with Fastmail for near-instant message loading.
• Privacy & Security First: No added third-party servers, tracking scripts or zero analytics. Emails render inside an isolated viewer.
• Live Toolbar Badge: Always know when you have incoming mail with an automatic, low-power unread badge right on your extension icon.
• Clean, Distraction-Free UI: A modern, uncluttered interface built to let you check and read unread messages quickly without losing your workflow.

Installation

Install the official extension directly from the Chrome Web Store.

Project Structure

• src/extension/: Chrome Extension application:
  • background/: Service Worker handling JMAP queries, token validation, and background alarm polling.
  • popup/: Svelte 5 application rendering the toolbar popup interface.
  • options/: Svelte 5 application for managing the Fastmail API token connection.
  • services/: Client services and messaging abstractions.
• src/site/: Project homepage web application (Features, Installation, Develop, Legal).
• src/shared/: Shared components (PageShell, Header, NavSidebar, Legal), unified router, types, and styles.

Local Development & Testing

1. Install dependencies:

   npm install

2. Run automated tests:

   npm test

3. Type check:

   npm run check

4. Start Vite development server (with HMR via @crxjs/vite-plugin):

   npm run dev

5. Load in Chrome:

   • Navigate to chrome://extensions/.
   • Enable Developer mode (top right).
   • Click Load unpacked and select the dist/ directory.

Production Build

• Build Chrome Extension (dist/):

  npm run build

  Minifies and bundles all extension assets into dist/. Zip the dist/ directory contents for Chrome Web Store submission.

• Build Project Homepage (dist-site/):

  npm run build:site

  Generates the static project website with HTML5 path routing and 404 fallback into dist-site/ (ready for GitHub Pages or static web servers).

• Build Both:

  npm run build:all

Contributing and Security Guidelines

See DEVELOPMENT.md.

License

This project is licensed under the Apache License 2.0. See the LICENSE file for the full license text.

Disclaimer

Checker for Fastmail is an independent open-source project and is not affiliated with, sponsored by, or endorsed by Fastmail Pty Ltd. Fastmail is a registered trademark of Fastmail Pty Ltd.