YAML Validator
Validate YAML syntax and check for errors
YAML Input
Validation Result
What is YAML Validator?
YAML Validator is a free online tool that checks your YAML (YAML Ain't Markup Language) code for syntax errors and validates it against the official YAML specification. Whether you're debugging Docker Compose files, Kubernetes configs, CI/CD pipelines, or learning YAML, our validator instantly tells you if your YAML is valid or where the errors are. Before deploying, make sure to use our YAML Formatter to clean up your files, or convert from other formats using our JSON to YAML converter.
According to YAML specification, YAML validation is crucial for ensuring data integrity. Our validator follows the official YAML standards, so you can trust the results. Valid YAML gets a green badge, invalid YAML shows you exactly what's wrong. After validation, you might want to minify your YAML for production or convert it to JSON for API use.
Everything runs in your browser – your YAML never leaves your computer. Fast, secure, and completely free.
What Makes This Tool Different
Instant Validation
Paste your YAML and get results right away. Valid YAML gets a green badge, invalid YAML shows you exactly where the problem is.
Detailed Error Messages
When something's wrong, we tell you the exact line, column, and what went wrong. No guessing – you'll know exactly what to fix.
File Upload Support
Got a big file? Just upload it. No need to copy-paste those massive YAML configs or data files.
Sample Data
Try it out with sample data. We've got examples of both valid and invalid YAML so you can see how it works.
Standards Compliant
We validate against the official YAML specification. If it passes here, it'll work anywhere – Docker, Kubernetes, CI/CD tools, you name it.
Syntax Highlighting
Nice syntax highlighting makes it easy to spot problems before you even validate. Visual feedback helps catch issues early.
How It Works
Paste or Upload YAML
Paste your YAML code into the left editor, or click "Upload" to load a file. You can also click "Valid Sample" or "Invalid Sample" to see examples of both valid and invalid YAML.
Automatic Validation
The validator automatically checks your YAML as you type. The right panel shows the validation result with a clear badge – green for valid, red for invalid. If there are errors, you'll see detailed error messages.
Fix and Verify
If your YAML is invalid, use the error messages to fix the issues. Common problems include incorrect indentation, missing colons, or invalid characters. Fix the errors and watch the validation status update in real-time.
When You'd Actually Use This
Docker Compose
Validate Docker Compose YAML files before deploying. Catch syntax errors early in development. Works great for docker-compose.yml files. After validation, use our YAML Formatter to ensure consistent formatting.
Kubernetes Configs
Before deploying, validate your Kubernetes YAML manifests. One syntax error can break your entire deployment. Catch it early with our validator. You can also convert to JSON if needed for certain Kubernetes tools.
CI/CD Pipelines
Validate GitHub Actions, GitLab CI, or other CI/CD YAML configs. Catch errors before they break your pipelines.
Learning YAML
New to YAML? Use the validator to check your work. Practice writing YAML and see if it's valid before using it in your projects.
Common Questions
Is my YAML data stored?
Nope. Validation happens right in your browser using JavaScript. Your YAML never leaves your computer.
What makes YAML invalid?
Common issues include: incorrect indentation, missing colons, invalid characters, incorrect list syntax, or mixing tabs and spaces. Our validator catches all of these.
Does it validate against YAML Schema?
This tool validates YAML syntax only, not YAML Schema. For schema validation, you'll need specialized tools that support schema validation.
What YAML standards does it follow?
We follow the YAML specification. If it validates here, it's valid YAML.
Can I validate large files?
Yes. Since validation happens in your browser, performance depends on your device. Small files validate instantly. Very large files (10MB+) might take a few seconds.
Why does my YAML show as invalid?
Check the error message – it tells you exactly what's wrong. Common fixes: check indentation (YAML is indentation-sensitive), ensure colons are present after keys, verify list syntax, and check for tabs (use spaces instead).
Other YAML Tools You Might Need
Validation is just one step. Here are other tools that work well together:
Need to learn more about YAML? Check out the official YAML.org website or the comprehensive YAML specification.