Free Online Tool

Format and validate YAML

Paste YAML code, get cleanly formatted output with syntax validation. Catch errors instantly. Works entirely in your browser.

Your files never leave your browser. All processing happens locally.
Examples
18 lines · 279 chars
Valid YAML
Comments will be removed during formatting

What does a YAML formatter and validator do?

A YAML formatter cleans up messy YAML — normalizing indentation and structure — while a validator checks it for syntax errors in real time. Together they turn inconsistent config files into well-formed, readable YAML you can trust before committing.

Paste your YAML and the tool reformats it with consistent 2- or 4-space indentation and flags any syntax errors with line numbers as you type, using the js-yaml parser. It supports standard YAML 1.2 features — multi-document files, anchors, aliases, complex keys, sequences, and mappings. Note that comments are removed during formatting, because the parser converts YAML to a data structure before re-serializing. Everything runs locally in your browser.

FAQ

Common questions

Is this tool free?

Yes. The YAML formatter and validator is completely free with no usage limits, no account, no watermarks, and no hidden fees.

Is my data private?

Your YAML never leaves your browser. All parsing and formatting happen locally on your device using js-yaml. Nothing is uploaded to any server.

What YAML features are supported?

All standard YAML 1.2 features including multi-document files, anchors, aliases, complex keys, sequences, and mappings. The formatter preserves your data structure while normalizing indentation. Note: YAML comments are removed during formatting, as the parser converts YAML to a data structure before re-serializing.

Does it validate YAML syntax?

Yes. The tool validates your YAML in real-time as you type and shows detailed error messages with line numbers for any syntax issues.

Can I customize the indentation?

Yes. You can choose between 2-space and 4-space indentation. The formatter applies your preference consistently across the entire document.

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