YAML Formatter & Validator - Online YAML Pretty Print Tool

What is YAML Formatter & Validator?

YAML Formatter is a tool that formats YAML text into a readable, indented form or validates its syntax. YAML (YAML Ain't Markup Language) is a data serialization format widely used in configuration files for Kubernetes, Docker Compose, and GitHub Actions. In Format mode, output is re-generated with the selected indent size. In Validate mode, syntax errors are shown with line and column numbers.

See also: JSON ⇔ YAML

How to Use

1. Paste YAML into the input area
2. Select mode (Format / Validate)
3. In Format mode, select indent size
4. Click the button to execute

Usage Examples

Input:
database:
  host: localhost
  port: 5432
  name: mydb

After formatting (2 spaces):
database:
  host: localhost
  port: 5432
  name: mydb

Practical use: Copy a Kubernetes Manifest YAML and format/validate it with this tool

FAQ

Is my data sent to a server?

No. All processing happens in your browser.

Are YAML comments preserved?

No. Comments are lost during formatting due to js-yaml's behavior.

Is multi-document YAML (--- separator) supported?

No. Only the first document is processed.

Does it support YAML 1.2?

js-yaml broadly supports YAML 1.2. Using JSON_SCHEMA enables stricter parsing.

Can I change the indent size?

Yes. In Format mode you can choose from 2 spaces, 4 spaces, or tab.

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