YAML Validator & Formatter

What is YAML?

YAML (YAML Ain't Markup Language) is a human-friendly data format used heavily for configuration: Docker Compose, Kubernetes, CI pipelines, and many app config files. It favours indentation and minimal punctuation over the brackets and quotes of JSON, which makes it readable but also sensitive to small mistakes. This tool validates YAML, reports the exact error line, and converts between YAML and JSON.

YAML uses spaces, never tabs

The single most important YAML rule: indentation must use spaces, not tabs. The spec forbids tabs for indentation, and a stray tab is one of the most common reasons a file fails to parse. Consistent two-space indentation is the usual convention. The validator normalises indentation and flags structural problems so you can fix them quickly.

Common YAML errors

• Using tabs instead of spaces for indentation.
• Inconsistent indentation levels within the same block.
• Missing the space after a colon in a key-value pair.
• Unquoted strings that contain special characters like ":" or "#".
• Misaligned list items under a key.

YAML vs. JSON

YAML and JSON can represent the same data, and in fact every JSON document is valid YAML. JSON is stricter and more compact, ideal for machine-to-machine transfer, while YAML is easier for humans to write and supports comments, which JSON does not. Converting between them (as this tool does) is handy when a system expects one format but you have the other.