YAML Syntax Checker

Check whether YAML is syntactically valid. Supports multi-document files (--- separators). Schema validation (Kubernetes, OpenAPI, etc.) is not performed.

  • Runs entirely in your browser
  • No data stored or sent to a server
  • Free forever — no signup
  • Instant conversion

Input and Output

Use the interactive encoder and decoder on this page to process your text.

Learn more about YAML validation

How to Validate YAML Syntax

YAML Validation

When to Validate YAML

Validate YAML before deploying configs, pushing CI workflow changes, or applying Kubernetes manifests. Catch indentation errors and syntax issues early instead of at deploy time.

Common YAML Errors

  • Tabs instead of spaces for indentation
  • Inconsistent indent levels in nested structures
  • Unquoted special characters in scalar values
  • Missing colons after keys

Common Mistakes

  • Assuming valid syntax means valid Kubernetes schema — use kubeval separately
  • YAML 1.1 truthy values (yes/no) surprising JSON converts

Developer Tips

  • Validate in CI: yamllint or parse step before deploy
  • Format after fixing errors for readable error context
  • Quote strings that look like booleans or numbers if you need literal text

Frequently asked questions

Does validation check schema or just syntax?

This tool checks YAML syntax only. It does not validate against Kubernetes, OpenAPI, or other schemas.

Can I validate multi-document YAML?

Yes. Files with --- separators are validated document by document. Each document is reported separately in the output.