Concourse vs GitLab CI: What are the differences?
Concourse: Pipeline-based CI system written in Go. Concourse's principles reduce the risk of switching to and from Concourse, by encouraging practices that decouple your project from your CI's little details, and keeping all configuration in declarative files that can be checked into version control; GitLab CI: GitLab integrated CI to test, build and deploy your code. GitLab offers a continuous integration service. If you add a .gitlab-ci.yml file to the root directory of your repository, and configure your GitLab project to use a Runner, then each merge request or push triggers your CI pipeline.
Concourse and GitLab CI can be primarily classified as "Continuous Integration" tools.
"Real pipelines" is the primary reason why developers consider Concourse over the competitors, whereas "Robust CI with awesome Docker support" was stated as the key factor in picking GitLab CI.
Concourse is an open source tool with 3.99K GitHub stars and 482 GitHub forks. Here's a link to Concourse's open source repository on GitHub.
According to the StackShare community, GitLab CI has a broader approval, being mentioned in 210 company stacks & 93 developers stacks; compared to Concourse, which is listed in 18 company stacks and 17 developer stacks.