YAML Formatter & Validator

Check YAML before using it

Paste a YAML document, choose two- or four-space indentation, and select Format and validate. Use Convert to JSON when you want to inspect the data model without YAML's presentation details.

Why YAML errors are easy to miss

YAML uses indentation to express nesting. A misplaced space can move a setting into another object, while a tab may stop parsing entirely. Unquoted values can also be interpreted as numbers, booleans, dates, or nulls. Validation answers whether the document parses; it does not prove that Kubernetes, Docker Compose, GitHub Actions, or another consumer accepts the resulting structure.

Worked example

Use Load example or copy this complete block with its real line breaks:

service:
  image: app:latest
  ports:
    - 8080
    - 8443
  environment:
    LOG_LEVEL: info

Formatting keeps the mapping and list hierarchy visible. The JSON view shows the same parsed keys and values using braces and brackets. If a list item loses its indentation, the parser reports a structural error instead of silently placing it under the intended key.

Formatting can normalize presentation

The formatter parses and writes YAML again. It preserves values and document order for normal mappings, sequences, anchors, aliases, and multi-document input, but comments and original quoting choices may be lost. Do not use formatted output when comments, handcrafted scalar styles, or byte-for-byte layout are part of the deliverable. Review diffs before committing configuration.

Secrets and schema limitations

Processing stays in this browser tab, which is useful for configuration containing internal names. Still avoid pasting production secrets into any environment you do not control. This page checks YAML syntax only. It does not apply a Kubernetes schema, validate a GitHub Actions workflow, resolve includes, render Helm templates, or verify that referenced files and environment variables exist.

YAML FAQ

Does valid YAML mean valid configuration?

No. Each application imposes its own keys, types, and rules after YAML parsing.

Why did quotes disappear?

The serializer may choose a simpler valid representation for a parsed scalar. Review values that resemble booleans, dates, or numbers.

Can I use tabs for indentation?

No. YAML structure uses spaces; choose two or four here.