8.4. The GitHub Marketplace
Not every tool a team needs is built into GitHub directly — the Marketplace is where third-party functionality plugs in.
💡 First Principle: The GitHub Marketplace is a directory of third-party Apps and Actions that extend GitHub's native functionality — integrations for project management, code quality, deployment, and more — that a repository or organization can install rather than build from scratch. Listings fall into two broad categories: Apps, which integrate with GitHub's platform more broadly (often via webhooks and permissions), and Actions, which plug directly into GitHub Actions workflows (5.1) as reusable steps.
⚠️ Exam Trap: Marketplace listings are third-party extensions layered on top of GitHub's native features — installing one requires explicitly granting it permissions, the same care you'd apply to any external integration with access to your repositories.
Reflection Question: A team wants to add a code-quality checker as a step in their existing GitHub Actions workflow, rather than building one from scratch. Where would they look for a ready-made option?
