YAML Validator

What is YAML Validator?

YAML Validator checks YAML documents for syntax errors, reports issues with precise line and column numbers, and displays the parsed document as a tree structure. It validates against the YAML 1.2 specification and catches common mistakes like incorrect indentation, tab characters (which YAML forbids), duplicate keys, and type coercion surprises. The tool also displays the parsed data types for each value.

DevOps engineers validating infrastructure configuration, backend developers debugging YAML configs, and platform engineers reviewing Kubernetes manifests. The tool runs entirely in your browser — your data never leaves your device.

How to Use YAML Validator

1. Paste your YAML content into the editor
2. View instant validation results — green for valid, red with error details for invalid
3. Click on any error message to jump to the exact line and column in the editor
4. Expand the parsed tree view to see how the YAML parser interprets your document structure
5. Fix highlighted issues and re-validate until the document passes

Common Use Cases

• Validating Kubernetes YAML manifests before applying them with kubectl
• Checking GitHub Actions workflow files for syntax errors that would cause pipeline failures
• Debugging Docker Compose files that fail to parse with cryptic error messages
• Verifying Ansible playbook YAML syntax before running against production infrastructure
• Validating Helm chart values.yaml files with complex nested structures

Pro Tips

• YAML never allows tab characters for indentation — always use spaces (typically 2). Many hard-to-debug YAML errors are caused by invisible tab characters mixed with spaces
• Unquoted strings that look like numbers or booleans get auto-converted — 1.0 becomes a float, true becomes a boolean. Always quote values that should remain strings
• Duplicate keys are silently allowed by some parsers (the last value wins) — this tool warns about them because duplicate keys almost always indicate a mistake

Why Use This Tool?

• Privacy-first: All processing happens locally in your browser. No data is transmitted to any server.
• No installation required: Works in any modern browser on desktop or mobile.
• Completely free: No account, no credit card, no usage caps.
• Fast and reliable: Powered by modern Web APIs for near-instant results.

Related Concepts

Learn more about related topics: YAML 1.2, YAML anchors, Kubernetes manifest, Helm templates.

Frequently Asked Questions