YAML Formatter & Validator — Free Online Tool
Paste any YAML document and instantly format it with consistent indentation. Live validation shows a green/red badge as you type. Uses js-yaml v4 with safe load by default — !! type constructors that could execute JavaScript are disabled. Supports Kubernetes configs, GitHub Actions, docker-compose, and any standard YAML.
100% client-side. No uploads. Your data never leaves your browser.
How to use YAML Formatter & Validator
- Paste YAML into the input area.
- The live badge shows valid/invalid as you type.
- Click 'Format YAML' to apply consistent indentation.
- Copy or download the formatted output.
Frequently Asked Questions
Is it safe to paste untrusted YAML?
Yes. js-yaml v4 uses safe load by default, which disables the !! type constructors that could execute arbitrary JavaScript.
Does this support YAML anchors and aliases?
Yes. Anchors (&anchor) and aliases (*anchor) are parsed and resolved. The noRefs option is set to true so the output expands aliases fully.
What YAML version does this support?
YAML 1.1 and 1.2 (as supported by js-yaml v4). Most Kubernetes, docker-compose, and CI/CD YAML files are compatible.
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