Concourse vs Testrail: 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; Testrail: Efficiently manage, track and organize your software testing efforts. TestRail helps you manage and track your software testing efforts and organize your QA department. Its intuitive web-based user interface makes it easy to create test cases, manage test runs and coordinate your entire testing process.
Concourse can be classified as a tool in the "Continuous Integration" category, while Testrail is grouped under "Test Management".
Concourse is an open source tool with 3.92K GitHub stars and 472 GitHub forks. Here's a link to Concourse's open source repository on GitHub.