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YAML Formatter & Validator

Format and validate YAML, and catch syntax errors.

Free browser toolRuns in your browserNo sign-up
Configuration validation studio

Parse and normalize YAML before configuration reaches production

Validate YAML syntax, report parser errors and generate consistently indented output locally without reordering your mapping keys.

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input size

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output size

YAML input

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Formatted YAML

No output yet
Source input is preserved until you explicitly replace it.
Private by design. Input is processed inside this browser tab and is not sent to ToolsOnDuty.

About the YAML Formatter & Validator

YAML is a human-friendly format for configuration and data, but its indentation-based syntax is easy to get wrong.

Paste your YAML and this tool parses it, reports any syntax error, and re-serialises it with clean, consistent indentation.

Parsing and formatting happen entirely in your browser, so your configuration never leaves your device.

Key features

  • Validate YAML and report errors
  • Re-indent with consistent spacing
  • Handles nested maps and lists
  • Preserves mapping-key order
  • Copy and explicit .yaml download
  • Runs entirely in your browser

How to use

  1. 1Paste or load YAML, or start with the configuration sample.
  2. 2Run Validate & format.
  3. 3Fix any reported parser error before output is generated.
  4. 4Copy or download the normalized .yaml result.

Examples

Format nested YAML
Input: user: name: Ada roles: [admin, editor]
Output: Consistently indented YAML

The formatter also reports invalid YAML instead of silently changing it.

Frequently asked questions

What does the validator check?
It checks that the YAML is syntactically valid and parses correctly. If not, it shows the parser error so you can fix it.
Is my YAML uploaded?
No. Everything runs in your browser.
Can it convert YAML to JSON?
This tool focuses on formatting and validating YAML. For conversion, format here first, then use a dedicated converter.

Continue your workflow

Open a related tool to prepare your files or refine the finished result.