• UX and Frontend guides
• Backend guides
  • General
  • Things to be aware of
  • Rails Framework related
  • Debugging
  • Git specifics
  • API
  • GitLab components and features
  • Import and Export
• Performance guides
• Database guides
• Integration guides
• Testing guides
• Refactoring guides
• Deprecation guides
• Documentation guides
• Internationalization (i18n) guides
• Analytics Instrumentation guides
• Experiment guide
• Build guides
• Compliance
• Domain-specific guides
• Technical Reference by Group
• Other development guides
• Other GitLab Development Kit (GDK) guides

Feature development

Consult these topics for information on contributing to specific GitLab features.

UX and Frontend guides

• GitLab Design System, for building GitLab with existing CSS styles and elements
• Frontend guidelines
• Emoji guide

Backend guides

General

• Software design guides
• GitLab EventStore to publish/subscribe to domain events
• GitLab utilities
• Newlines style guide
• Logging
• Dealing with email/mailers
• Kubernetes integration guidelines
• Permissions
• Code comments
• Windows Development on GCP
• FIPS compliance
• Gemfile guidelines
• Ruby upgrade guidelines

Things to be aware of

• Gotchas to avoid
• Avoid modules with instance variables, if possible
• Guidelines for reusing abstractions
• Ruby 3 gotchas

Rails Framework related

• Routing
• Rails initializers
• Mass Inserting Models
• Issuable-like Rails models
• Issue types vs first-class types
• DeclarativePolicy framework
• Rails update guidelines

Debugging

• Pry debugging
• Sidekiq debugging
• VS Code debugging

Git specifics

• How Git object deduplication works in GitLab
• Git LFS

API

• API style guide for contributing to the API
• GraphQL API style guide for contributing to the GraphQL API

GitLab components and features

• Developing against interacting components or features
• Manage feature flags
• Implementing Enterprise Edition features
• Accessing session data
• How to dump production data to staging
• Geo development
• Redis guidelines
  • Adding a new Redis instance
• Sidekiq guidelines for working with Sidekiq workers
• Working with Gitaly
• Advanced search integration docs
• Working with merge request diffs
• Approval Rules
• Repository mirroring
• Uploads development guide
• Auto DevOps development guide
• Renaming features
• Code Intelligence
• Feature categorization
• Wikis development guide
• Image scaling guide
• Cascading Settings
• Shell commands in the GitLab codebase
• Value Stream Analytics development guide
• Application limits
• AI features
• Application settings
• Remote Development
• Markdown (GLFM) development guide

Import and Export

• Add new relations to the direct transfer importer
• Principles of importer design
• Working with the GitHub importer
• Import/Export development documentation
• Test Import Project
• Group migration
• Export to CSV

Performance guides

• Performance guidelines for writing code, benchmarks, and certain patterns to avoid.
• Caching guidelines for using caching in Rails under a GitLab environment.
• Merge request performance guidelines for ensuring merge requests do not negatively impact GitLab performance
• Profiling a URL or tracking down N+1 queries using Bullet.
• Cached queries guidelines, for tracking down N+1 queries masked by query caching, memory profiling and why should we avoid cached queries.
• JSON guidelines for how to handle JSON in a performant manner.
• GraphQL API optimizations for how to optimize GraphQL code.

Database guides

See database guidelines.

Integration guides

• Integrations development guide
• GitLab for Jira Cloud app
• Security Scanners
• Secure Partner Integration
• How to run Jenkins in development environment

The following integration guides are internal. Some integrations require access to administrative accounts of third-party services and are available only for GitLab team members to contribute to:

• Jira integration development
• GitLab for Slack app development

Testing guides

• Testing standards and style guidelines
• Frontend testing standards and style guidelines

Refactoring guides

• Refactoring guidelines

Deprecation guides

• Deprecation guidelines

Documentation guides

• Writing documentation
• Documentation style guide
• Markdown

Internationalization (i18n) guides

• Introduction
• Externalization
• Translation

Analytics Instrumentation guides

• Service Ping guide
• Internal Events guide

Experiment guide

• Introduction

Build guides

• Building a package for testing purposes

Compliance

• Licensing for ensuring license compliance

Domain-specific guides

• CI/CD development documentation
• Sec Section development documentation

Technical Reference by Group

• Create: Source Code BE

Other development guides

• Defining relations between files using projections
• Compatibility with multiple versions of the application running at the same time
• Features inside .gitlab/
• Dashboards for stage groups
• Preventing transient bugs
• GitLab Application SLIs
• Spam protection and CAPTCHA development guide
• RuboCop development guide

Other GitLab Development Kit (GDK) guides

• Using GitLab Runner with the GDK
• Using the Web IDE terminal with the GDK
• Gitpod configuration internals page