GitLab CI is a feature that helps perform the Continuous Integration (CI) of software components. When several developers work together using a versioning system, problems can arise when changes made by one developer break the product as a whole. The best way to make sure this happens less often, or at least early in the process, is to use integration tests more frequently, hence the name continuous.

GitLab CI was launched as a standalone project in 2013, but was later integrated into the main GitLab package. Combined with the GitLab Runner software, this feature has been very popular with developers and is an important driver of the business. It also enabled GitLab to build their product into a solution that not only does CI, but even continuous delivery up to production environments. The current product vision for GitLab is to serve as a complete DevOps life cycle product, from idea to production.

Forrester classified GitLab as a leader in CI in The Forrester Wave: Continuous Integration Tools, Q3 2017. This is shown in the following diagram:

Feedback, one of the important aspects of the Extreme Programming (XP) movement, is an important element of GitLab CI. It also serves as a way to communicate between developers.