CircleCI vs. GitHub Actions vs. GitLab: Key Differences
Blog post from Sauce Labs
CircleCI and GitHub Actions offer pre-built containers for testing purposes, while GitLab CI/CD requires downloading the latest tools, which can add an extra step to the YAML configuration file. CircleCI has a lower price point but less functionality included in the price compared to GitHub Actions and GitLab CI/CD. GitHub Actions is the least mature of the three options discussed here and only supports GitHub repositories. GitLab CI/CD offers a free self-hosted option, but its per-user pricing makes it the most expensive option if you want to use it with full enterprise functionality. CircleCI is arguably the best option overall due to its purpose-built focus on CI/CD pipelines, while GitLab and GitHub may be suitable for organizations that aim to simplify their support structures by utilizing fewer vendors.