YAML Validator

Check YAML 1.2 syntax, duplicate keys and bounded alias references. Paste one or several documents to inspect parser errors; this validator does not check an application schema.

Free to useNo sign-upRuns in your browser

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Enter the inputs, then select Validate YAML.

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How YAML Validator works

The validator parses YAML 1.2 documents with strict syntax and unique keys, resolves references under an alias-count limit, and reports the document total.

A valid result concerns YAML syntax and reference consistency. It does not prove that a Kubernetes manifest, CI file, or another application configuration follows its schema.

Preserve actual indentation instead of aligning text by appearance alone.

An indented YAML document connected to a structural validation view. — Illustration of the YAML Validator workflow.

How to use YAML Validator

Paste YAML source to check parsing under the supported YAML 1.2 rules.

Supply the YAML documents

Paste the YAML source with meaningful indentation, quoted values, anchors, and references intact. Separate multiple documents using the YAML document marker when needed, staying within the document and alias limits.

Supply the YAML documents

YAML Validator native input panel with the actual YAML settings used for this example. — Configure YAML; select Validate YAML.

Validate syntax and references

Run the validator and inspect the Valid YAML result or reported parser problem. On success, the result shows how many documents were checked with the strict YAML 1.2 parser.

Validate syntax and references

YAML Validator actual result panel showing Valid YAML. — Submitted result: Valid YAML. Documents: 2.

Read the validation scope

Review the syntax-and-bounded-alias note before handing the configuration to an application. This result does not check a Kubernetes, CI, or other application schema, so validate those requirements separately.

Read the validation scope

YAML Validator actual documents region and result note after submitting the pictured settings. — Review Documents in this YAML Validator example. Read the result note.

When to use YAML Validator

Use syntax validation as one step before an application specific configuration review.

Validate a YAML configuration edit

Validate a YAML file after editing a nested setting or adding a list item. This can catch a syntax mistake before application testing. Keep the intended behavior test separate, because changing a valid value can still produce an unwanted configuration.

Validate a YAML configuration edit

Developer input and configuration represented by document cards. — Prepare the input. Concept illustration.

Check multiple YAML documents

Check a source containing document separators and inspect the reported document count. Confirm the destination supports the same number and arrangement of documents. A parser accepting several documents does not establish that an application will process all of them.

Check multiple YAML documents

A developer example flowing from input to reviewed output. — Inspect an example. Concept illustration.

Find duplicate mapping keys

Use the strict check when a copied configuration may repeat the same key in one mapping. Resolve the duplication deliberately by checking the intended source value. Do not rely on another parser silently choosing one of the conflicting entries.

Find duplicate mapping keys

Developer output handed to the next stage of a workflow. — Use the result in your workflow. Concept illustration.

Read YAML duplicate-key and alias checks

Use the validation result to assess the supported YAML syntax before checking an application-specific schema.

Duplicate keys are rejected under this YAML 1.2 check. Unsupported tag warnings are also treated as a validation problem rather than evidence that the data has been safely interpreted.

Alias expansion is bounded, and the input supports from one to twenty documents. These are implementation limits, not a statement that all other YAML processors accept the same constructs.

Validate YAML Review the output

A developer result reviewed alongside its source. — Review the returned output. Concept illustration.

Check syntax and unsupported features

Inspect indentation, tags, keys, and references in the original document when a validation error appears.

Preserve actual indentation instead of aligning text by appearance alone. If a tag or alias causes rejection, check whether the target application requires that feature before replacing it with a guessed value.

The validator does not check an application schema or generate a corrected file. Use the original source and the consumer documentation when deciding how to resolve a valid but unsuitable configuration.

Validate YAML Check the source