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YAML Validator & Formatter

Paste your YAML to validate, format, convert to JSON, or minify. Everything runs in your browser — your data stays private.

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YAML parse error fixes and prevention

YAML (YAML Ain't Markup Language) is a human-readable data serialization format commonly used for configuration files, data exchange, and infrastructure-as-code tools like Docker Compose, Kubernetes, Ansible, and GitHub Actions.

Unlike JSON, YAML uses indentation to denote structure, supports comments with #, and provides a more readable syntax for complex nested data. For a detailed comparison, see our JSON vs YAML vs TOML comparison guide.

Features

Frequently Asked Questions

What is YAML and what is it used for?
YAML (YAML Ain't Markup Language) is a human-readable data serialization format that uses indentation to represent structure. It is widely used for configuration files in tools like Docker Compose, Kubernetes, Ansible, GitHub Actions, and CI/CD pipelines. YAML supports comments, multiline strings, and complex nested data while remaining easy to read and write.
What are the most common YAML syntax errors?
The most common YAML mistakes include: using tabs instead of spaces for indentation (YAML only allows spaces), inconsistent indentation levels, missing colons after mapping keys, forgetting the dash-space prefix for list items, unquoted strings that look like booleans or numbers (e.g. 'yes', 'no', 'on', 'off'), and duplicate keys in the same mapping.
How do I convert YAML to JSON?
You can convert YAML to JSON by parsing the YAML document into a data structure and then serializing it as JSON. This online tool does it automatically: paste your YAML and click "Convert to JSON". Since YAML is a superset of JSON, every JSON document is valid YAML, but YAML features like comments and anchors have no direct JSON equivalent and are stripped during conversion.
Keyboard Shortcuts
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