YAML Formatter & Validator
Validate YAML as you type, re-indent it with your preferred indentation, sort keys, and view it as JSON.
Runs entirely in your browser.
YAML Formatting and Validation Tool
About YAML Formatting
YAML (YAML Ain't Markup Language) is a human-readable data serialization format widely used for configuration files such as Docker Compose, Kubernetes manifests, GitHub Actions workflows, and CI pipelines. Because YAML relies on whitespace indentation to express structure, a single misplaced space or an accidental tab character can break a configuration file — which makes a validator a handy companion when editing YAML by hand.
This tool validates your YAML as you type and reports the first problem it finds together with the line number where it occurred. It can re-indent your document with 2 or 4 spaces, optionally sort mapping keys alphabetically, and show the parsed result as JSON so you can see exactly how your data will be interpreted by an application.
Note: the built-in parser handles the common subset of YAML — nested mappings, lists, strings, numbers, booleans, and null. It does not support anchors and aliases (&/*), multi-document streams (---), block scalars (| and >), or flow-style collections, and quoted multi-word keys are not handled specially. For full YAML 1.2 coverage, use a dedicated library. Everything runs locally in your browser. See also the JSON to YAML Converter.
