What is YAML?
YAML (YAML Ain't Markup Language) is a human-friendly, indentation-based data serialization format used mainly for configuration files. It represents the same data as JSON — scalars, lists and mappings — but with cleaner syntax, comments and multi-line strings, making it popular in CI/CD, Docker and Kubernetes.
YAML uses indentation (spaces, never tabs) to show structure instead of brackets. Mappings are key: value, lists use -, and it supports comments (#), multi-line strings and anchors/references for reuse. Because YAML is a superset of JSON, any JSON is valid YAML.
Its readability makes it the default for human-edited configuration — GitHub Actions, Docker Compose, Kubernetes manifests — where comments and clean diffs matter.
YAML tools
YAML Formatter & Validator
Validate, reformat, and minify YAML in your browser. Catches syntax errors with line numbers.
Open toolYAML to JSON Converter
Convert YAML to JSON in your browser. Catches syntax errors with parser messages.
Open toolJSON to YAML Converter
Convert JSON to YAML in your browser. YAML 1.2 spec.
Open toolFrequently asked questions
Is YAML the same as JSON?
YAML is a superset of JSON — every JSON document is valid YAML. YAML adds comments, anchors and indentation-based syntax for readability.
Why does YAML use indentation?
Indentation replaces brackets to keep config files clean and readable. It must be spaces, not tabs, and consistent.