Which YAML version is validated?

YAML 1.2 by default, with an option for 1.1. Validation is based on the well-tested `yaml` library.

Are malicious YAML inputs handled safely?

Yes. The parser caps alias expansion to protect against “billion laughs”-style denial-of-service documents.

Does it support multiple documents?

Yes. Documents separated by --- are each validated, and errors are reported per document.

YAML Validator

Validate YAML against the 1.2 specification and see exactly where issues occur. The validator understands multiple documents, anchors and aliases, tags, and block scalars, and guards against malicious alias-expansion inputs.

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Processed locally in your browser

Inputyaml

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Results

Results will appear here after you run a check.

YAML○ Not checked0 lines0 chars0 B

How to use the yaml validator

Paste or upload YAML.
Validation runs as you type and on demand with the Validate button.
Errors include the exact location the parser reports.
Multiple documents, anchors, and block scalars are all understood.

Example: Catching bad indentation

Input

a:
  b: 1
   c: 2

Output

Error: bad indentation of a mapping entry (line 3).

Frequently asked questions

Which YAML version is validated?: YAML 1.2 by default, with an option for 1.1. Validation is based on the well-tested `yaml` library.
Are malicious YAML inputs handled safely?: Yes. The parser caps alias expansion to protect against “billion laughs”-style denial-of-service documents.
Does it support multiple documents?: Yes. Documents separated by --- are each validated, and errors are reported per document.