YAML Formatter & Validator

How to use

1. Enter YAML

   Enter YAML in the textarea, or select or drop a YAML file.

2. Choose an operation

   Choose Validate or Pretty. Reading a file does not start an operation automatically.

3. Review the result

   Review diagnostics or the Pretty result, then copy only a successful Pretty result.

Scope of the result

Supports one YAML 1.2 Document, a 5 MiB input limit, and a 20 MiB Pretty output limit. Files are decoded as strict UTF-8 with only an initial BOM removed. Processing stays in the browser.

Frequently asked questions

Does it support multiple documents or YAML 1.1?

It handles one YAML 1.2 Document only. Multiple documents, custom tag definitions, and YAML 1.1 compatibility are not included.

Are comments and anchors preserved?

Yes. Pretty uses the YAML Document node, so comments, anchors, and aliases are not discarded by object conversion. Exact whitespace and scalar-style preservation is not guaranteed.

Is my YAML uploaded?

No. Loading, diagnostics, and formatting run entirely in your browser.