YAML Validator & Formatter
Validate and format YAML files online. Check for syntax errors and view parsed structure.
YAML Input
Parsed as JSON
What is YAML Validator & Formatter?
YAML (YAML Ain't Markup Language) is a human-readable data format used extensively in DevOps, configuration files, and CI/CD pipelines. This validator checks your YAML for syntax errors before deployment, preventing cryptic runtime errors in Docker Compose, Kubernetes, GitHub Actions, and other YAML-dependent tools.
How to Use This Tool
- Paste your YAML content (or load the Docker Compose example)
- Click Validate YAML to check for syntax errors
- View the parsed JSON structure to verify correctness
- Use Format to normalize indentation
Common Use Cases
- Validating Docker Compose files before deployment
- Checking Kubernetes manifests for syntax errors
- Debugging GitHub Actions workflows
- Verifying CI/CD pipeline configurations
Frequently Asked Questions
Why does YAML require spaces instead of tabs?
YAML uses indentation to define structure. Tabs can have different widths in different editors, causing inconsistent parsing. Spaces provide consistent, predictable indentation. Always use 2 spaces per indentation level.
What's the most common YAML error?
Incorrect indentation is the #1 cause of YAML errors. Other common issues include: missing colons after keys, unquoted strings containing special characters (like colons or brackets), and inconsistent spacing.
How do I include special characters in YAML values?
Wrap values containing special characters in single or double quotes. For example: key: "value with: colon" or key: 'value with special chars'. Multiline strings use | (literal) or > (folded) block indicators.
Is my YAML file uploaded to a server?
No, all validation happens entirely in your browser. Your configuration files never leave your device, making this tool safe for validating files containing secrets or sensitive data.