YAML Validator & Linter

Check YAML syntax, find errors, and enforce best practices.

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What is YAML Validation & Linting?

YAML validation checks whether your YAML document is syntactically correct and can be parsed without errors. Linting goes further by checking for style issues, best practices, and potential problems that won't cause parse errors but could lead to bugs or maintenance issues.

Common issues detected by this tool include:

  • Syntax errors — Invalid indentation, malformed mappings, unclosed quotes
  • Duplicate keys — Same key defined multiple times in the same mapping
  • Indentation issues — Mixed tabs and spaces, inconsistent indentation depth
  • Trailing spaces — Unnecessary whitespace at line endings
  • Line length — Lines exceeding recommended maximum length
  • Empty values — Keys with no values that might be unintentional
  • Boolean style — Inconsistent use of true/false vs yes/no
  • Missing document start — Missing --- separator

How to Use

  1. Paste your YAML — Enter or paste your YAML content into the input area. Click Example to load sample data with intentional issues to demonstrate the linter.
  2. Validate — Click Validate to check basic YAML syntax. Errors will be shown with line and column numbers.
  3. Validate & Lint — Click Validate & Lint to run both syntax validation and a comprehensive set of best-practice checks.
  4. Review issues — Issues are grouped by severity: errors (red), warnings (amber), and info (blue). Each issue shows the line number and description.
  5. View structure — After validation, a tree view of the YAML document structure is shown to help you navigate nested data.

Frequently Asked Questions

What is the difference between Validate and Validate & Lint?

Validate checks if your YAML is syntactically valid and can be parsed. Validate & Lint does the same check but also runs additional checks for style, best practices, and potential issues that aren't syntax errors.

Is my YAML data stored on a server?

No. All processing happens entirely in your browser using JavaScript. Your YAML data never leaves your device.

What YAML version is supported?

This tool uses the js-yaml library which supports both YAML 1.1 and YAML 1.2 specifications.

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