actionlint

actionlint is a static checker for GitHub Actions workflow files. It analyzes workflow YAML to catch syntax mistakes, invalid keys, expression errors, incorrect action inputs, and workflow configuration problems before they break CI. The tool also performs strong type checks for GitHub Actions expressions, which helps detect nonexistent properties and type mismatches. It can validate reusable workflows, workflow calls, glob syntax, runner labels, cron syntax, and job dependencies. actionlint also integrates with ShellCheck and pyflakes to inspect scripts written inside run: blocks. It is especially useful for developers and teams that rely heavily on GitHub Actions and want faster, more reliable workflow feedback.