YAML Validator

YAML Validator is a free online tool for validating YAML (YAML Ain't Markup Language) syntax and converting it to JSON format. YAML is a human-readable data serialization standard commonly used for configuration files and data exchange between languages with different data structures.

Our YAML Validator instantly checks your YAML for syntax errors and provides detailed error messages with line and column numbers to help you quickly identify and fix issues. When your YAML is valid, it displays the parsed JSON output for easy verification.

Whether you're a DevOps engineer working with Kubernetes manifests, a developer managing application configs, or anyone working with YAML files, our tool provides instant validation with clear feedback. All processing happens in your browser, ensuring your configuration data remains private and secure.

YAML is readable and full of traps, and validation catches most of them. Tabs are the first: they are forbidden as indentation anywhere in the file, so an editor set to insert tabs will produce something that cannot parse no matter how right it looks. The second is type coercion, and it is famous. Under YAML 1.1 rules the unquoted words yes, no, on and off are booleans, which is why a country list containing NO for Norway comes back as false. Version numbers behave similarly: 1.10 is a float and reads as 1.1, while 1.10.2 is a string. Quote anything that should stay text. Duplicate keys are the third, accepted silently by some parsers and rejected by others, which makes them a genuine source of environment-specific bugs.