YAML Validator — Syntax Error Finder
Validate YAML syntax instantly in your browser. Get real-time feedback on errors with exact line and column numbers. Supports multi-document YAML and shows document statistics including nesting depth and key counts.
How to Use YAML Validator — Syntax Error Finder
How to Use the YAML Validator:
Paste Your YAML: Type or paste your YAML content into the input area. Validation happens in real-time as you type — no button press needed.
Read the Status Banner: A green "Valid YAML" banner means your YAML is syntactically correct. A red "Invalid YAML" banner means there is an error.
Fix Errors: When invalid, the error card shows the exact line number, column number, and error message. Use these to locate and fix the issue in your YAML.
Review Document Statistics: When valid, the statistics panel shows line count, top-level keys, total keys, maximum nesting depth, and document count.
Use Examples: Click the example buttons (App Config, Docker Compose, GitHub Actions, Invalid Demo) to load sample YAML and explore how the validator works.
Clear: Click the Clear button to reset the input and start fresh.
Common YAML Errors and Fixes:
- Tabs instead of spaces: YAML requires spaces for indentation — never tabs. Your editor may silently insert tabs.
- Inconsistent indentation: All sibling keys must be at the same indentation level. YAML is whitespace-sensitive.
- Unclosed quotes: A string starting with a quote must end with the matching quote on the same logical line.
- Colon without space: In a mapping, the colon must be followed by a space (key: value, not key:value).
- Special characters in values: Values containing colons, curly braces, or square brackets should be quoted.
- Duplicate keys: YAML technically allows duplicate keys but behavior is undefined — most parsers use the last value.
Common Use Cases:
- Validating Docker Compose files before running docker-compose up
- Checking GitHub Actions workflow syntax before pushing
- Verifying Kubernetes manifests before applying them
- Debugging Ansible playbooks and Helm chart values
- Validating configuration files for frameworks like Rails, Django, and Spring Boot
Frequently Asked Questions
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