How it works
Paste or type YAML in the editor. As you type, the page parses it with a full YAML 1.2 parser and reports the first error with its line and column. Hit Format to normalize indent and quoting. Toggle the output panel to JSON to see the structured equivalent.
Why this site is fast
- Pure static HTML — no framework runtime, no analytics bloat.
- All parsing happens locally in your browser.
- No tracking, no ads, no cookies.
Guides
- YAML vs JSON: when to use which — where each format wins, where each falls down, and the four rules that prevent every common YAML bug.
- YAML multiline strings (| vs >) — all five block scalar styles, chomping (-, +), and the mistakes that cause extra newlines or weird indent drift.
- YAML anchors and aliases — & / *, the merge key (<<:), and when to use a templating engine instead.
FAQ
Is my YAML sent to a server?
No. Validation, formatting, and the YAML→JSON conversion all happen in your browser using a YAML 1.2 parser bundled with the page.
Why does my indentation fail validation?
YAML is whitespace-sensitive. The most common cause is mixing tabs and spaces, or sibling keys at different indent levels. The error message shows the exact line and column where the parser gave up.
Can I convert YAML to JSON?
Yes — toggle the output panel to JSON. The converter parses to a JS object then serializes as JSON, so anchors, aliases, and YAML-specific tags are resolved before output.
Does this support YAML 1.2?
Yes, including null variants (~, null, empty), boolean variants (true, yes, on), block and flow styles, multiline strings (|, >), anchors (&) and aliases (*), and merge keys (<<).
Why do I get a warning instead of an error?
Warnings flag YAML that parses successfully but has ambiguous or deprecated syntax — for example, a Python-style boolean (Yes/No) that's allowed in 1.1 but not preferred in 1.2. The output is still valid; the warning is informational.