jeffwidman/yamllint

YAML is a popular file format for configuration, the kind of file that tells an app or service how to behave. But YAML is picky about spacing, indentation, and structure. A single extra space or misaligned line can break things in confusing ways. yamllint catches those problems before they cause headaches. It goes beyond just checking whether your YAML is valid. It also flags things like duplicate keys, lines that are too long, trailing spaces, and inconsistent indentation, the kind of issues that won't necessarily break your file but make it harder to read and maintain over time. You run it from the command line, pointing it at a file or a whole directory. It then reports back any issues it finds. You can use the default rule set, pick a more relaxed preset, or write your own configuration file that specifies exactly which rules matter to you and which ones you'd rather ignore. You can also add special comments directly inside your YAML files to turn off specific checks for individual lines or sections, and you can tell it to skip certain files entirely using patterns similar to a .gitignore file. This is useful for anyone working with YAML regularly, developers, DevOps folks, or anyone maintaining configuration files for tools like CI pipelines, Kubernetes, or static site generators. If your project has dozens of YAML files with multiple people editing them, running this tool (often as part of an automated check before code gets merged) keeps everything clean and consistent. It's written in Python and can output results in a format that code editors like Vim or Emacs can read, so you can get feedback as you type. The project is licensed under GPL version 3, and full documentation is available on Read the Docs.