YAML Validator - Validate YAML Syntax Online

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.

How to Use the YAML Validator

Follow these steps to validate your YAML. Each step uses the actual buttons and panels on this page.

Paste, Upload, or Load Sample

Paste YAML into the left editor, or click Upload to load a file. Click Valid Sample or Invalid Sample to see telecomm examples. Valid example:

subscriber:
  subscriberId: SUB-1001
  plan: Unlimited 5G
  dataUsage: 45.2
  status: active
  carrier: Verizon

View Validation Result

The right panel shows the result: green badge for valid, red for invalid. Invalid YAML displays detailed error messages (line, column, and cause).

Fix and Verify

Use error messages to fix indentation, missing colons, or invalid characters. Validation updates in real-time. All processing runs in your browser.

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 Specification 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. Check out the Docker Compose for more details.

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: