YAML Validator
Validate YAML syntax instantly with parsed structure preview, clear error messages, and browser-based processing. Perfect for config files, CI workflows, infrastructure definitions, and frontmatter checks before deployment.
What is YAML Validator?
The YAML Validator checks whether a string is valid YAML. It parses the input using a JavaScript YAML parser and reports the exact line number and description of any syntax error. Common errors like incorrect indentation, invalid characters, and malformed structures are detected. All processing happens in the browser.
How does YAML Validator work?
This tool passes your YAML text to a parser and catches any thrown errors. When an error occurs, it extracts the line number and message from the error. For valid YAML, it confirms the parse succeeded and shows the top-level type (mapping, sequence, scalar).
Key Features
- Validates YAML syntax with error positions
- Detects indentation errors and invalid characters
- Shows line numbers for errors
- Confirms valid YAML with type information
- Handles nested structures
- Real-time validation as you type
- Copy validation report
- Runs in the browser with no uploads
Common Use Cases
Validating Kubernetes manifests before deployment
Check a Kubernetes YAML file for syntax errors before applying it with kubectl.
Debugging CI/CD pipeline configs
Validate a GitHub Actions or GitLab CI YAML file to find syntax issues before pushing.
Checking Docker Compose files
Verify that a docker-compose.yml is syntactically valid before starting containers.
Verifying configuration files
Validate a YAML config file to ensure it will parse correctly at runtime.
How to Use This Tool
Paste YAML
Enter YAML text in the input area.
Validate
Click Validate or wait for real-time validation.
Review the result
If valid, the tool confirms it. If invalid, it shows the line number and error description.
Pro Tips
- 1
YAML is indentation-sensitive. The most common errors are wrong indent levels.
- 2
Tabs are not allowed in YAML. Use spaces for indentation.
- 3
The tool shows the exact line number so you can find errors quickly.
- 4
For Kubernetes configs, always validate before deploying.
Frequently Asked Questions
What YAML errors are detected?
The tool detects all syntax errors including incorrect indentation, invalid characters, malformed mappings and sequences, unclosed quotes, and duplicate keys.
Does it show where the error is?
Yes. The error message includes the line number where the parser encountered the problem.
Is my YAML uploaded to a server?
No. All validation happens in your browser using JavaScript. Nothing is transmitted.
Can I validate large YAML files?
Yes. The tool handles YAML of any size that fits in browser memory.
Does it validate against a schema?
No. The tool only checks YAML syntax. It does not validate against Kubernetes, Docker, or other schemas.