Development
Outside of docs
- CONTRIBUTING.md main contributing guide
 - PROCESS.md contributing process
 - GitLab Development Kit (GDK) to install a development version
 
Styleguides
- API styleguide Use this styleguide if you are contributing to the API.
 - Documentation styleguide Use this styleguide if you are contributing to documentation.
 - Writing documentation
 - SQL Migration Style Guide for creating safe SQL migrations
 - Testing standards and style guidelines
 - UX guide for building GitLab with existing CSS styles and elements
 - Frontend guidelines
 - SQL guidelines for working with SQL queries
 - Sidekiq guidelines for working with Sidekiq workers
 Gemfileguidelines
Process
- Generate a changelog entry with 
bin/changelog - Limit conflicts with EE when developing on CE
 - Guidelines for implementing Enterprise Edition feature
 - Code review guidelines for reviewing code and having code reviewed.
 - Merge request performance guidelines for ensuring merge requests do not negatively impact GitLab performance
 
Backend howtos
- Architecture of GitLab
 - Gotchas to avoid
 - How to dump production data to staging
 - Instrumentation
 - Performance guidelines
 - Rake tasks for development
 - Shell commands in the GitLab codebase
 - Sidekiq debugging
 - Object state models
 - Building a package for testing purposes
 - Manage feature flags
 - View sent emails or preview mailers
 - Working with Gitaly
 
Databases
- Merge Request Checklist
 - What requires downtime?
 - Adding database indexes
 - Post Deployment Migrations
 - Foreign Keys & Associations
 - Serializing Data
 - Polymorphic Associations
 - Single Table Inheritance
 - Background Migrations
 - Storing SHA1 Hashes As Binary
 - Iterating Tables In Batches
 - Ordering Table Columns
 - Verifying Database Capabilities
 - Hash Indexes
 - Swapping Tables
 
Internationalization (i18n) guides
Compliance
- Licensing for ensuring license compliance