YAML Formatter & Converter

About YAML Formatter & Validator

The YAML Formatter & Validator uses the js-yaml library to parse your YAML document, detect indentation and syntax errors, and convert it to prettified JSON for inspection — or convert JSON back to YAML. It renders the JSON output as a collapsible interactive tree so you can navigate deeply nested configuration structures without scrolling through thousands of lines.

YAML powers configuration for Docker Compose, Kubernetes, GitHub Actions, Ansible, and many other tools, making a reliable validator essential for catching whitespace errors before deployment. Everything runs locally in your browser — no YAML content is ever sent to a server.

Common Use Cases

• Validating Kubernetes manifests or Helm chart values files before running kubectl apply
• Debugging GitHub Actions workflow YAML that fails with cryptic parse errors in CI
• Converting a YAML configuration to JSON so it can be used in a JavaScript application or REST API body
• Checking Docker Compose files for incorrect indentation that prevents containers from starting

How to Use

1. Choose conversion direction: YAML → JSON or JSON → YAML
2. Paste your document into the Input panel, or click Load Example to try a sample config
3. Click Convert to transform the document, or Validate to check syntax without converting
4. Click Swap to move the output back to the input and reverse the conversion direction

Frequently Asked Questions

Why does YAML lose comments when converted to JSON?

The JSON specification does not support comments, so they are dropped during conversion. If you need to preserve comments, keep the YAML source as your canonical config and only convert to JSON for runtime use.

What YAML version does this tool support?

The tool uses js-yaml 4.x, which supports the YAML 1.2 specification. This is the same version used by most modern tooling including Kubernetes and Helm. Anchors, aliases, and multi-document streams are supported.

Can I validate YAML without converting it?

Yes. Click the Validate button to check whether your YAML parses successfully without generating any output. A green success message confirms the document is valid; a red message shows the exact line and column of the syntax error.