Check YAML online for common syntax issues before using a configuration file. Review indentation, tabs, duplicate keys, brackets, and quoting problems, with line-by-line warnings and a downloadable report.
Useful for Docker Compose, Kubernetes, GitHub Actions, CI/CD configs, app settings, and API documentation.
Paste YAML code and check it for common syntax errors, warnings, and indentation issues.
| Type | Line | Message | Fix Suggestion |
|---|---|---|---|
| Validation report will appear here. | |||
A YAML Validator helps you find syntax mistakes before your configuration file breaks a build, deployment, or application.
Find common YAML problems like tabs, invalid indentation, missing colons, duplicate keys, and unbalanced brackets.
See errors and warnings with line numbers so you can quickly locate and fix the issue.
Copy the validation report or download it as a text file for debugging, documentation, or client work.
YAML validation checks whether a YAML file follows correct structure and readable formatting rules. YAML is widely used for configuration files because it is clean and human-readable, but it is also sensitive to indentation.
This browser-based YAML validator highlights common mistakes before YAML is used in Docker Compose, Kubernetes, GitHub Actions, CI/CD pipelines, API docs, or application settings. It performs helpful rule-based checks, not complete YAML specification parsing. For indentation and spacing cleanup, try the YAML Formatter before reviewing the final configuration in your own YAML parser.
| Issue | Meaning | Common Fix |
|---|---|---|
| Tabs | YAML should use spaces, not tabs | Replace tabs with spaces |
| Bad Indentation | Nested structure may be wrong | Use consistent 2 or 4 spaces |
| Missing Colon | Key-value separator may be missing | Add colon after the key |
| Duplicate Keys | Same key appears at same level | Rename or remove duplicate key |
| Unbalanced Brackets | Inline arrays or objects may be broken | Close brackets correctly |
Validate YAML code in three simple steps.
Add YAML code from Docker, Kubernetes, GitHub Actions, CI/CD, app configs, or API documentation.
The tool checks common YAML syntax problems, indentation issues, tabs, duplicate keys, and brackets.
Review the report, fix line-based errors, copy the report, or download it for later review.
Common questions about YAML syntax, indentation, validation, and configuration files.