Overview
Getting Started
Working On Firefox
Firefox User Guide
Source Code Documentation
The Firefox Build System
Testing & Test Infrastructure
Releases & Updates
Localization & Internationalization
Firefox and Python
Metrics Collected in Firefox
For Firefox quality, Mozilla has different processes to report defects. In parallel, over the years, Mozilla developed many tools around bug management.
Fuzzing
Autonag - Source
Bugbug - Blog post about triage / Blog post about CI
Bugmon - Source
Mozregression - Source