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YAML Formatter & Validator

Validate, reformat, and minify YAML in your browser. Catches syntax errors with line numbers.

Free No signup Client-side Privacy friendly

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How to use

  1. 1 Paste your YAML.
  2. 2 Pick Reformat for indented block style, Flow for compact JSON-like form.
  3. 3 Optionally sort keys for diff-friendly output.
  4. 4 Copy or download.

Why use this tool

  • Powered by js-yaml — round-trips your YAML through a real parser.
  • Validation catches syntax errors with parser messages.
  • Sort-keys mode is great for stable diff in version control.
  • Pure client-side, your config never uploads.

Frequently asked questions

Why does my anchor/alias get expanded?

YAML anchors (&) and aliases (*) are resolved on parse — the output represents the materialized data. If you need to preserve aliases as-is, do not reformat.

Will key order change?

No, unless you enable Sort keys. By default, the parser preserves order as written.

What about YAML 1.1 vs 1.2 quirks?

js-yaml uses YAML 1.2 semantics by default — "yes/no/on/off" are strings (not booleans). If your input depends on YAML 1.1, expect quoted-string output.

Summary

YAML Formatter & Validator is a free developer utility by Zerethon Tools. Validate, reformat, and minify YAML in your browser. Catches syntax errors with line numbers. Runs entirely in the browser — no signup, no upload.

Category
Developer
Pricing
Free
Privacy
Browser-based
Signup
Not required

Privacy

Your data never leaves your browser unless explicitly stated. YAML Formatter & Validator runs entirely client-side — no server upload, no logging, no tracking of your input.

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