Firefox Source Tree Documentation

Overview

• A Glossary of Common Terms
• A Quick Guide to Mozilla Applications
  • Gecko
  • Firefox for Desktop
  • Firefox for Android
  • Firefox for iOS

Getting Started

• Getting Set Up To Work On The Firefox Codebase

Working On Firefox

• Working on Firefox
  • Firefox Contributors’ Quick Reference
  • Working with stack of patches Quick Reference
  • Pocket Guide: Shipping Firefox
  • Editor / IDE integration
  • Getting reviews
  • Levelling up
  • How to submit a patch
  • Data Collection
  • Data Review
  • Introduction to Jujutsu
  • Searchfox
  • Firefox AI Coding Policy
  • Code Review FAQ
  • Reviewer Checklist
  • Capturing a minidump
  • Debugging A Hang On macOS
  • Debugging A Minidump
  • Debugging Firefox with GDB
  • Debugging Firefox with LLDB
  • Debugging Firefox with Pernosco
  • Debugging Firefox with rr
  • Debugging Firefox with Valgrind
  • Debugging On macOS
  • Debugging On Windows
  • Debugging WebRTC Calls
  • Symbolicating TreeHerder stacks locally
  • How to get a process dump with Windows Task Manager
  • How to get a stacktrace for a bug report
  • How to get a stacktrace with WinDbg
  • Understanding Crash Reports
  • Configure Development Certificate
  • Signing Local macOS Builds
  • Firefox Source Code Directory Structure
  • Understanding Artifact Builds
  • Firefox for Mobile Devices
  • Supported Build Hosts and Targets
  • Working with ESR115
  • Engineering Show and Tell
  • Filing good bugs
• Bug Handling
  • Guides
  • Policies
  • Processes
  • Related documentation

Firefox User Guide

• Firefox DevTools User Docs
  • The Core Tools
  • More Tools
  • AI Tools
  • Connecting the Developer Tools
  • Debugging the browser
  • Extending DevTools
  • Migrating from Firebug
  • Contribute

Source Code Documentation

• Governance
  • Overview
  • Modules
• Firefox Front-end
  • How-To’s
  • Address Bar
  • Browser Usage Telemetry
  • Frontend Code Review Best Practices
  • Command Line Parameters
  • Browser Startup
  • Category manager indirection (callModulesFromCategory)
  • CustomizableUI Component
  • Enterprise Policies
  • Web Apps in Firefox
  • Form Autofill
  • Firefox Home (New Tab)
  • Firefox Welcome Experience (about:welcome)
  • Installer
  • Installation Attribution
  • Default Browser Agent
  • Migration
  • PageDataService
  • Places
  • Messaging System
  • Search UI
  • tabbrowser
  • Touch Bar
  • UITour
  • Firefox Branding
  • Storybook for Firefox
  • Reusable UI widgets
  • Other types of UI Widgets
  • Lit
  • XUL and HTML
  • Figma Code Connect
  • Design Tokens
  • Backup Component
  • Sidebar
  • moz-cached-ohttp Protocol
• DOM
  • DOM IPC
  • DOM Navigation
  • Push
  • Script Security
  • Xray Vision
  • DOM Workers & Storage
  • Web IDL bindings
  • IOUtils Migration Guide
  • Federated Credential Management
  • Implementing specifications using WHATWG Streams API
  • Use Counters
  • Logging native keyboard and IME event handler behavior
• Editor
  • Editor module structure
  • Editor module specific rules
  • IME handling guide
• Style system (CSS) & Layout
  • Style System Overview
  • Layout Overview
  • Dynamic change handling along the rendering pipeline
  • Layout Engine Visual Tests (reftest)
  • Layout Code Reviewer Checklist
  • Layout Debugger
  • AccessibleCaret
• Graphics
  • Rendering Overview
  • Layers History
  • Asynchronous Panning and Zooming
  • Silk Overview
  • Moz2D
• Processes, Threads and IPC
  • IPDL: Inter-Thread and Inter-Process Message Passing
  • Gecko Processes
  • Shutdown handling of processes
  • Utility Process
• Firefox DevTools Contributor Docs
  • Automated tests
  • Files and directories
  • Tool Architectures
  • Frontend
  • Backend
  • Performance
  • Preferences
  • Recurring tasks
• Toolkit
  • Profiles Service
  • JavaScript Logging
  • Add-on Manager
  • Autocomplete
  • Background Task Mode
  • Crash Manager
  • Crash Reporter
  • Internal URLs
  • Search Service
  • IP Protection
  • Shield Recipe Client
  • Nimbus
  • Messaging System Schemas
  • Picture-in-Picture
  • Prompts
  • Subprocess Module
  • Telemetry
  • Firefox on Glean (FOG)
  • Toolkit Modules
  • Toolkit Widgets
  • Fingerprinting Resistance
  • URL Classifier
  • WebExtensions API Development
  • Managing the built-in en-US dictionary
  • Application Update
  • Anti-Tracking
  • Translations
  • Session Store
• SpiderMonkey
  • Building and testing SpiderMonkey
  • Running Automated JavaScript Tests
  • Hacking Tips
  • SavedFrame
  • JavaScript Language Feature Checklist
  • So You Want to Add a Bytecode Op
  • Adding Use Counter Telemetry to the JS Engine
  • How SpiderMonkey Optimizes
  • Inline caches / CacheIR
  • Debugger API
  • Components of SpiderMonkey
• JS Loader
  • System Modules
  • JS Loader APIs
• GeckoView
  • Documentation
  • More information
• Fenix
  • Acronym Dictionary
  • Addressing a performance regression
  • Architecture Decisions
  • Architecture Overview
  • Crash Monitoring
  • Creating a release branch
  • Data practises
  • Development Test Plan
  • Fennec Legacy: Migration
  • Firebase Cloud Messaging for WebPush
  • Firefox for Android Team Processes
  • Home
  • Implementing Telemetry
  • Implementing a Nimbus Experiment
  • List of Fenix Threads
  • Logging Crash Information
  • Metric Feature Tags
  • Debug settings menu instructions
  • Telemetry - Implementation, Reviews, Renewals
  • Creating Glean Annotations
  • Data review
  • Test Telemetry Pings
  • Working with Strings
  • Adjust
  • Certificates
  • Crash Reporting
  • Experiments
  • Manual Testing
  • Metrics Definitions
  • Release Checklist
  • Startup Performance
  • Substituting Local GeckoView
  • Sync Integration Tests
  • Telemetry
  • UI Tests
• Focus for Android
  • Architecture Decisions
  • Battery Debugging
  • Content blocking
  • Crash Reporting with Sentry
  • Development Custom GeckoView
  • Feature & Issue workflow
  • Running GeckoView in a debug environment
  • Home
  • Homescreen Tips
  • Multisession architecture
  • Recommended pre-push hook
  • Release Process
  • Release tracks
  • Removing strings
  • Sprint Process
  • Telemetry
  • UI Test
• WebIDL
  • Overview
  • WebIDL source file flavors
  • Producing C++ code
  • Requirements
• libpref
  • High-level design
  • Low-level details
• Networking
  • How-to’s
  • Tutorials
  • Deep Dives
  • References
• Remote Protocols
  • Common documentation
  • Protocols
  • Architecture
  • Bugs
  • Communication
• Services
  • Remote Settings
  • Sync
• Permissions
  • Permission Manager
  • Browser-Scoped Permissions
  • Remote Permissions
  • Unused Permission Expiry
• File Handling
  • URI Loader Service
  • External Helper App Service
• Firefox on macOS
  • Using macOS APIs
  • A primer on macOS SDKs
• Firefox on Windows
  • Windows DLL Blocklisting
  • Windows Pointing Device Support in Firefox
  • Windows Limited Access Features
• Firefox AI Runtime
  • Architecture
  • APIs
  • Notifications
  • Models management
  • How to perftest a model
  • WebExtensions AI API
• Accessibility
  • Guidelines for New Contributors
  • Architecture
  • Document Accessibility Lifecycle
  • GeckoView Thread Topography
  • Colors and High Contrast Mode
  • HCM Settings
  • High Contrast Mode (HCM) Media Queries
  • HCM CSS Self-Check Guide
  • Tagged PDF Output
• Media Playback
  • MediaFormatReader
• Code quality
  • Static Analysis
  • Linting
  • Coding style
  • TypeScript
• Writing Rust Code
  • Basics
  • Rust/C++ interop
  • Rust Update Policy
  • XPCOM components in Rust
• Rust Components
  • Topic Guides
  • API References
  • Developing Rust Components
  • uniffi-bindgen-gecko-js developers guide
• Gecko Profiler
  • Profiler Code Overview
  • Buffers and Memory Management
  • Instrumenting JavaScript
  • Instrumenting Rust
  • Instrumenting Android
  • Markers
  • Profiling Memory
  • Profiling Sandbox violations (Linux)
• Performance
  • General Performance references
  • Memory profiling and leak detection tools
  • Profiling and performance tools
  • Power Profiling
  • Performance Metrics
• Database bindings (SQLite, KV, …)
  • Storage Warnings
• XPCOM
  • Consuming XPCOM functionality
  • Tooling around XPCOM
  • Writing new XPCOM interfaces/classes
• NSPR
  • Documentation
  • Getting NSPR
  • Community
  • Related Topics
• Network Security Services (NSS)
• Web Security Checks in Gecko
  • Key Concepts and Terminology
  • Loading Lifecycle in Firefox
  • Security Checks During Loading

The Firefox Build System

• Mach
• Pushing to Try
• Build System
• Firefox CI and Taskgraph
• Managing Documentation
• Vendoring Third Party Components

Testing & Test Infrastructure

• Automated Testing
• Understanding Treeherder Results
• Sheriffed intermittent failures
• Turning on Firefox tests for a new configuration
• Avoiding intermittent tests
• Debugging Intermittent Test Failures
• Testing Policy
• Configuration Changes
• Browser chrome mochitests
• Chrome Tests
• Marionette
• geckodriver
• Test Verification
• WebRender Tests
• Mochitest
• XPCShell tests
• TPS
• web-platform-tests
• GTest
• Fuzzing
• Sanitizer
• Performance Testing
• Code coverage
• Testing & Debugging Rust Code

AI Agent Tools

• AI Agent Tools for Firefox Development

Releases & Updates

• Mozilla Update Infrastructure
• Watershed Updates
• Desupport Updates
• Update Verify

Localization & Internationalization

• Internationalization
  • Locale management
  • UI Internationalization
  • ICU
  • ICU4X
• Localization
  • Localization Overview
  • Fluent
  • Migrating Strings From Legacy or Fluent Files
  • Single localization source for multiple builds
  • L10N Glossary

Firefox and Python

• mozbase
• Using third-party Python packages

Metrics Collected in Firefox

• Metrics