Does valid mean my app will accept the file?

No. Valid means the YAML syntax parsed. Required keys, types, and product-specific rules are outside this tool.

Will it fix my indentation?

No. The input stays as you typed it. Use the error location to edit it yourself.

No. Validation runs in your browser on the text in the editor.

Checks whether the YAML parses. The text in the editor is not rewritten.

Ctrl+Enter or ⌘+Enter runs this tool immediately.

YAML to check

Waiting for input.

Parsing stays in this browser. Input is not uploaded or saved.

Paste the YAML you want to check, or load the workflow sample.
Read the validation panel. Valid and invalid states use different wording, and errors name a line and column when available.
Fix the source yourself. Clear starts over. Sample replaces the editor with a known-valid document only when you ask it to.

This checks syntax against the YAML 1.2 core schema. It does not know whether the document matches a particular application's schema.
Duplicate keys are errors. The validator will not silently keep the last one.
A file of only comments has no document value. That is reported as valid YAML with no value, not as a repaired document.
The input is never rewritten, formatted, or auto-corrected.

A top-level mapping of two keys is valid. The summary counts keys and does not list them.

image: app:1.4
replicas: 2

An unclosed flow sequence is invalid. The panel reports the location and leaves the text in the editor.

steps: [build, test

Nested mappings are not allowed in compact mappings: Break the nested mapping onto its own indented line instead of putting it beside the parent key.
Unresolved alias: Define the anchor before the alias, or remove the alias. The validator does not invent the missing anchor.
Flow sequence must end with a ]: Close the bracket, or switch the sequence to block style with dashes.

Does valid mean my app will accept the file?: No. Valid means the YAML syntax parsed. Required keys, types, and product-specific rules are outside this tool.
Will it fix my indentation?: No. The input stays as you typed it. Use the error location to edit it yourself.
Is the document sent anywhere to be checked?: No. Validation runs in your browser on the text in the editor.

Kubernetes YAML syntax check
Check the YAML syntax of a Kubernetes manifest, including files with more than one document. This does not check apiVersion, required fields, or unknown kinds.
YAML to JSON converter
Convert YAML configuration to readable or compact JSON in the browser. Comments are dropped, and parse errors include line and column when the parser reports them.
JSON to YAML converter
Convert valid JSON into YAML with 2-space or 4-space indentation. Nested objects, arrays, and multiline strings are preserved, and invalid JSON is reported instead of repaired.