YAML Validator & Formatter
Validate YAML syntax, find errors with line numbers, and format your YAML files. All processing happens in your browser.
About YAML Validator
YAML (YAML Ain't Markup Language) is a human-readable data serialization format widely used for configuration files across modern development tools. From Kubernetes manifests and Docker Compose files to GitHub Actions workflows and Ansible playbooks, YAML is essential in DevOps and cloud-native development. However, YAML's indentation-based syntax makes it prone to subtle errors that can be difficult to spot. This validator helps you catch those errors instantly.
Unlike JSON, YAML uses whitespace indentation to define structure, which means a single misplaced space can completely change the meaning of your document or produce a parse error. Common pitfalls include mixing tabs and spaces, inconsistent indentation levels, unquoted strings that look like numbers or booleans, and missing colons or spaces after colons. This tool highlights the exact line where errors occur and provides clear error messages to help you fix issues quickly.
Features
Real-time validation with detailed error messages including line numbers. JSON output view to see exactly how your YAML will be parsed. YAML reformatting with consistent indentation. Statistics showing the number of keys, maximum nesting depth, and document size. All processing happens in your browser with complete privacy.
Common YAML Mistakes
Using tabs instead of spaces for indentation (YAML only allows spaces). Forgetting to quote strings that look like numbers, booleans, or null (e.g., "on", "yes", "3.0"). Missing a space after the colon in key-value pairs. Inconsistent indentation levels within the same block. Using special characters in unquoted strings without proper escaping.
FAQ
Q: Does this validator support all YAML features?
A: This validator supports the most commonly used YAML features including key-value pairs, nested objects, arrays, block scalars, flow collections, comments, and document start markers. Advanced features like anchors, aliases, and custom tags are detected and reported.
Q: Is my data safe?
A: Yes. All validation happens locally in your browser using JavaScript. No data is sent to any server.
Q: Can I use this for Kubernetes YAML files?
A: Yes. This tool validates general YAML syntax which covers Kubernetes manifests, Helm charts, Docker Compose files, and any other YAML-based configuration. Note that it validates YAML syntax only, not schema-specific rules.
Q: What's the difference between YAML validation and YAML linting?
A: Validation checks if YAML is syntactically correct and can be parsed. Linting goes further by checking for style issues like inconsistent quoting, key ordering, and line length. This tool focuses on validation with formatting capabilities to enforce consistent style.