YAML Formatter & Validator
Paste YAML to validate, auto-format, minify, or convert to JSON instantly. All processing runs in your browser.
Formatted YAML will appear here…Frequently Asked Questions
What is YAML and why do I need a formatter?
YAML (YAML Ain't Markup Language) is a human-readable data serialisation format commonly used for configuration files in Docker, Kubernetes, GitHub Actions, and many other tools. Indentation is significant in YAML — a single misplaced space can break your config. A formatter normalises indentation, removes accidental inconsistencies, and makes it immediately obvious whether your file is structurally valid.
Is my YAML data sent to a server?
No. All validation and formatting is performed entirely in your browser using the js-yaml library compiled to JavaScript. Your YAML — which may contain secrets, API keys, or environment variables — never leaves your machine. There are no server calls and no logging.
What is the difference between YAML and JSON?
JSON (JavaScript Object Notation) and YAML represent the same data structures but with different syntax. YAML uses indentation instead of braces and brackets, supports comments with #, and is generally more readable for humans. JSON is more portable and universally supported in APIs and code. The 'Convert to JSON' toggle in this tool lets you switch between the two instantly.
How does YAML validation work here?
The tool parses your YAML input using js-yaml on every keystroke. If parsing succeeds, the YAML is considered valid and the formatted output is shown. If parsing fails, the full error message from the parser — including the line and column where the problem was detected — is displayed in the error panel so you can fix it quickly.