Chrome to Firefox Extension Converter

A Rust-based CLI tool and WebAssembly library that converts Chrome Manifest V3 extensions to Firefox-compatible format.

Live Demo: https://otsobear.github.io/chrome2moz/

Why This Tool?

Firefox natively supports chrome.* APIs, but some Chrome-only APIs don't exist in Firefox. This tool:

• Detects 176 Chrome-only APIs (e.g., chrome.offscreen, chrome.declarativeContent, chrome.tabGroups)
• Converts manifests (service workers → event pages, permission separation)
• Provides runtime shims for Chrome-only APIs
• Checks keyboard shortcuts for conflicts with Firefox built-ins

Read more: ARCHITECTURE.md covers Chrome API detection system, detection scope, and keyboard shortcuts in detail.

Features

• Smart Detection: Identifies Chrome-only APIs that need conversion
• Manifest Transformation: Handles MV3 manifest differences for Firefox
• Keyboard Shortcut Checker: Detects conflicts with 60+ Firefox shortcuts
• Multiple Formats: Supports .crx, .zip, or unpacked directories
• Web Interface: Browser-based UI (no installation required)

Quick Start

Web UI (Recommended)

./build-wasm.sh
cd web && python3 -m http.server 8080
# Open http://localhost:8080

Drag & drop your Chrome extension ZIP, analyze, and download the converted Firefox version.

CLI

# Install
git clone https://github.com/OtsoBear/chrome2moz.git
cd chrome2moz
cargo build --release

# Analyze
./target/release/chrome2moz analyze -i ./chrome-extension

# Convert
./target/release/chrome2moz convert -i ./chrome-extension -o ./output

# List Chrome-only APIs
./target/release/chrome2moz chrome-only-apis

Options: --report (generate report), --yes (skip prompts), --preserve-chrome (keep both namespaces)

What Gets Converted

Chrome-Only APIs → Runtime shims provided for: - chrome.storage.session → In-memory polyfill - chrome.sidePanel → Firefox sidebarAction - chrome.offscreen → Web Workers/content scripts - chrome.declarativeContent → Content script patterns - chrome.tabGroups → No-op stub (Firefox doesn't support) - And more... (see ARCHITECTURE.md)

Manifest Changes: - background.service_worker → background.scripts (event page) - Add browser_specific_settings.gecko for Firefox ID - Separate permissions from host_permissions - Convert web_accessible_resources format - Handle importScripts() → Add to manifest

Firefox Compatibility Fixes: - Automatically disables browser.management.uninstallSelf() calls - Prevents extensions from self-destructing when detecting Firefox - See docs/FIREFOX_SELF_UNINSTALL_FIX.md for details

API Coverage

View Full API Status →

Testing in Firefox

1. Open about:debugging#/runtime/this-firefox
2. Click "Load Temporary Add-on"
3. Select the converted manifest.json or .xpi file

Check Browser Console (Ctrl+Shift+J) for any errors.

Important Notes

• Firefox supports chrome.* namespace natively - no need to rewrite to browser.*
• Static analysis has limits - runtime behavior differences need manual testing
• ~90% of conversions work automatically; remaining 10% may need manual adjustments
• See ARCHITECTURE.md for what's detected vs. what requires testing

Contributing

Contributions welcome! See ARCHITECTURE.md for architectural details.

cargo fmt && cargo clippy && cargo test

Resources

• Report Issues
• Architecture Documentation
• Live Demo
• API Implementation Status

License

MIT License - See LICENSE file for details.