YAML Validator - Check YAML Syntax Online
Paste YAML to instantly check for syntax errors like tabs, unmatched quotes, and invalid keys. Free online YAML validator.
YAML Input
Validation Result
Enter YAML on the left to validate.
How Does the YAML Validator Work?
This tool checks your YAML input for common syntax errors including tab characters (YAML requires spaces), unmatched quotes, and invalid key formatting. Paste or type your YAML on the left and see validation results on the right in real time.
Example
Valid YAML: name: John
age: 30 shows "Valid YAML ✓". Invalid YAML with tabs or unmatched quotes will display the error with its line number.
Common Use Cases
- Checking YAML configuration files before committing or deploying them.
- Debugging Docker Compose, Kubernetes, or CI/CD pipeline configs that fail to parse.
- Learning YAML syntax by seeing what causes validation errors in real time.
FAQs
Does this replace a full YAML parser?
No — this is a lightweight syntax checker that catches common mistakes like tabs, unmatched quotes, and bad key formatting. For full structural validation, use a dedicated YAML library.
Why doesn't YAML allow tabs?
YAML uses indentation to define structure, and the spec requires spaces (typically 2) for indentation. Tabs are explicitly forbidden because they can be displayed at different widths across editors, leading to ambiguous parsing.
Is my data uploaded?
No — all validation happens entirely in your browser. Nothing you paste is sent to any server.