Free YAML Validator

How to Validate YAML Online

Paste your YAML into the left panel and the validation result appears instantly on the right. A green checkmark means your YAML is valid. A red error shows the exact problem with line and column numbers. You can also drag and drop a .yaml or .yml file or use the upload button.

Common YAML Syntax Errors

The most frequent YAML errors are: inconsistent indentation (mixing tabs and spaces), missing colons after keys, incorrect nesting levels, unquoted strings that look like numbers or booleans, duplicate keys in the same mapping, and improperly closed multi-line strings or block scalars.

Frequently Asked Questions

How does the YAML validator work?

The validator parses your YAML using a standards-compliant parser and checks for syntax errors. If the YAML is valid, you'll see a green checkmark. If there are errors, you'll see the exact error message with location details.

Does it show error locations?

Yes — when your YAML is invalid, the validator shows the error message along with the line and column number where the problem was detected, so you can find and fix it quickly.

Can it fix errors?

No — the validator identifies and locates errors but does not auto-fix them. It shows you exactly where the problem is so you can correct it yourself. This ensures you understand and control every change.

Is it free?

Yes — completely free, forever. No sign-up, no account, no usage limits.

Is my data safe?

All validation happens locally in your browser using JavaScript. Your YAML is never uploaded to any server. It's safe to use with sensitive or proprietary data.

Can I also format YAML?

Yes — use the YAML Formatter to format, beautify, or minify your YAML with configurable indentation.