Validate YAML syntax and display parsed structure.
Results
What is YAML Validator?
YAML Validator checks your YAML syntax for errors including tab characters (not allowed in YAML), indentation issues, and duplicate keys. Shows line numbers for each issue found, with file size and structure stats.
How to use this tool
Paste your YAML content.
Click Validate to check syntax.
See errors (tabs, structural issues) and warnings (odd indentation, duplicates).
Review stats: line count, key count, depth, file size.
Fix reported issues and re-validate.
Frequently asked questions
Why does YAML not allow tabs?
YAML requires spaces for indentation — tabs are forbidden by specification. This avoids ambiguity since different editors display tabs at different widths. Configure your editor to insert spaces when you press Tab.
How many spaces for YAML indentation?
Two spaces is the convention, but any consistent number works. The key rule is consistency — every level must use the same number of spaces. Mixing 2 and 4 spaces at the same level causes errors.
What are common YAML mistakes?
Using tabs instead of spaces, inconsistent indentation, missing space after colon (key:value vs key: value), and unquoted strings that look like booleans (yes/no become true/false).
YAML vs JSON — when to use which?
YAML is more human-readable with less syntax noise — great for config files, Docker Compose, Kubernetes, and CI/CD. JSON is better for APIs and data interchange where strict parsing matters.