Why would a team choose GitHub over GitLab for an open-source project?

For open-source specifically, the pull is mostly about reach and ecosystem rather than raw feature depth. GitHub hosts the largest concentration of open-source contributors, so a project there is simply more discoverable to potential contributors who already have accounts and workflows built around GitHub.

Beyond discoverability, GitHub Actions' Marketplace gives open-source maintainers a huge library of ready-made steps (publishing to package registries, running linters, posting release notes) without writing custom automation from scratch. Features like "good first issue" labeling, GitHub Sponsors for funding maintainers, and tight integration with tools contributors already use (VS Code, Copilot) also lower the friction for a first-time contributor to get involved.

This isn't a universal win: GitLab's single-application model with built-in security scanning and CI/CD can appeal more to internal, closed-source DevOps teams that value a unified toolchain over external contributor reach, which is exactly the audience open-source projects don't primarily need to serve.