The Bazel project is led by a core group of contributors, initially Googlers, and managed by the community. The group of core contributors is self-managing - core contributors are added by two supporting votes from core contributors on the mailing list and no veto within four business days. We expect that new contributors will submit a number of patches before they become core contributors.

Accepting Contributions

Please also see our contribution guidelines.


We use the following rules for accepting code contributions. This is written from the perspective that there is a group of people who cooperatively support the project (the core contributors). In contrast, external contributors are not actively supporting the project, but just contributing individual changes. At this time, all core contributors work for Google (see below for the full list), but this will hopefully change over time.

  1. We require all contributors to sign Google's Contributor License Agreement.

  2. We accept well-written, well-tested contributions of rules written in Skylark, in a contrib/ directory or similar with clearly documented support policies.

  3. We accept well-written, well-tested bug fixes to built-in rules.

  4. We accept well-written, well-tested feature contributions if a core contributor assumes support responsibilities, i.e., readily answers support questions and works on bugs. This includes feature contributions from external contributors. If there is no core contributor to support a feature, then we will deprecate and subsequently delete the feature - we will give three months' notice in such cases.

  5. We will not accept untested changes, except in very rare cases.

  6. We require a pre-commit code review from a core contributor for all changes. For the time being, we will have to continue making changes across the internal and external code bases, which will be reviewed internal to Google.

  7. We will roll back changes if they break the internal development processes of any of the core contributors.

  8. We will move towards an open governance model where multiple parties have commit access, roll-back rights, and can provide explicit support for features or rules.

  9. We will work with interested parties to improve existing extension points and to establish new extension points if they do not run counter to the internal requirements of any of the core contributors.

Are you done open sourcing Bazel?

Open sourcing Bazel is a work-in-progress. In particular, we're still working on open sourcing:

  • Many of our unit and integration tests (which should make contributing patches easier).
  • Full IDE integration.

Beyond code, we'd like to eventually have all code reviews, bug tracking, and design decisions happen publicly, with the Bazel community involved. We are not there yet, so some changes will simply appear in the Bazel repository without clear explanation. Despite this lack of transparency, we want to support external developers and collaborate. Thus, we are opening up the code, even though some of the development is still happening internal to Google. Please let us know if anything seems unclear or unjustified as we transition to an open model.

Are there parts of Bazel that will never be open sourced?

Yes, some of the code base either integrates with Google-specific technology or we have been looking for an excuse to get rid of (or is some combination of the two). These parts of the code base are not available on GitHub and probably never will be.

Core Contributors

Contact the core team at