YAML Validator

Q: Which YAML version does it use?

YAML 1.2 via the widely used yaml JavaScript library, the same one many Node.js tools use.

Check a Kubernetes manifest, CI workflow or Compose file before you push it. Errors show the line, column and reason; valid YAML is shown as JSON so you can see how it was read.

Input · drop a file

name: deploy
on:
  push:
    branches: [main]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci
     - run: npm test

Parsed as JSON

The YAML mistakes that break builds

Inconsistent indentation — list items at a different depth from their siblings (the sample above has one).
Tabs — YAML forbids tab characters for indentation.
Duplicate keys — the second silently overwrites the first in many tools; this validator flags it.
Unquoted colons — title: Note: read me needs quotes around the value.

See how YAML was interpreted

The JSON preview shows exactly what a parser sees, which catches the silent problems: version: 1.10 becoming the number 1.1, or country: NO being read differently by YAML 1.1 tools.

Questions

Which YAML version does it use?

YAML 1.2 via the widely used yaml JavaScript library, the same one many Node.js tools use.

Does it validate Kubernetes or GitHub Actions schemas?

It checks YAML syntax, not the schema of a particular tool. A syntactically valid file can still have a misspelled field.