A committer is an individual who is permitted to modify the source code of a software project, that will be used in the project's official releases. To contribute source code to most large software projects, one must make modifications and then "commit" those changes to a central version control system, such as Git (or CVS).

In open-source software development, the committer role may be used to distinguish commit access, a specific type of responsibility, from other forms of contribution, such as triaging issues or organizing events. Typically, an author submits a software patch containing changes and a committer integrates the patch into the main code base of the project.

To have a "commit bit" on one's user account means that the user is permitted to contribute source code changes. This dates to the use of a literal binary digit to represent yes-or-no privileges in access control systems of legacy version control and software systems, such as BSD. The commit bit represents the permission to contribute to the shared code of a software project. It can be resigned or may be removed due to inactivity in the project, as dormant committer accounts can represent security risks.

Project committers are usually the lead developers of a project and are the ones responsible for the majority of changes. They are seen as trusted, responsible and reliable members of the project's community. Relatedly, committers are usually responsible for the review of patches submitted by members of the community for inclusion into the software. After a successful review, usually consisting of conformance to coding standards and ensuring it does not introduce any new bugs, the committer will commit that specific patch on behalf of the patch submitter.