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YAML Formatter & Validator — Reformat, Minify & Lint YAML

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

Free No signup Client-side Privacy friendly Updated

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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.

What is YAML Formatter & Validator?

A YAML Formatter is a tool that validates, reformats, and minifies YAML data. It checks the input for syntax errors and reports them with line numbers, re-indents valid documents into a consistent readable layout, and can compact them to reduce size. It runs entirely in the browser, processing YAML on the device without uploading it to a server.

How YAML Formatter & Validator compares to alternatives

YAML Formatter & Validator versus typical browser and desktop alternatives — features compared at a glance.
Feature Zerethon Tools Typical online tools Desktop apps
Signup required No Sometimes No (IDEs)
Data leaves device No Yes No
Validate + reformat + minify All three Sometimes Varies
Line-numbered errors Yes Sometimes Yes
Free Yes Yes (with ads) Often paid
Works offline Yes (after load) No Yes
Summary

YAML Formatter & Validator is a free 开发者 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
开发者
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.

Compare

JSON vs YAML YAML vs XML

Learn the basics

What is YAML?

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