YAML Formatter and Validator

YAML 1.2 format and validate via js-yaml. Flow style is expanded to block style, and parse errors report the exact line and column.

Indent

Sort mapping keys

Quote all strings

YAMLapiVersion: apps/v1
kind: Deployment
metadata:
   name: checkout
   labels:
       app:    checkout
spec:
  replicas: 3
  template:
    spec:
      containers:
        - name: checkout
          image: "registry.internal/checkout:1.4.0"
          ports:
          - containerPort: 8080
          env:
            - {name: LOG_LEVEL, value: info}
            - {name: TIMEOUT_MS, value: "2500"}

Formatted YAMLapiVersion: apps/v1
kind: Deployment
metadata:
  name: checkout
  labels:
    app: checkout
spec:
  replicas: 3
  template:
    spec:
      containers:
        - name: checkout
          image: registry.internal/checkout:1.4.0
          ports:
            - containerPort: 8080
          env:
            - name: LOG_LEVEL
              value: info
            - name: TIMEOUT_MS
              value: '2500'

YAML Formatter and Validator — Free Online Tool

Formats and validates YAML 1.2 with js-yaml, normalizing indentation, quoting and line width, optionally sorting mapping keys and forcing quotes, and reporting parse errors with the exact line and column, useful for cleaning up hand-edited Kubernetes manifests, GitHub Actions workflows and docker-compose files before they reach CI.

How to use the YAML Formatter and Validator

Open the tool above — it runs entirely in your browser, so your input never leaves this page.
Paste or type your input into the field, then press the relevant button (e.g. Encode / Decode, Generate, or Convert).
Copy the result from the output area with the copy button orCtrl/Cmd + C.
No signup, no upload, and no tracking — repeat as often as you need.

Frequently asked questions

Are my comments preserved when I format?

No. Formatting parses the document into a value and re-emits it, and js-yaml does not retain comments through that round trip. Format a copy if the comments matter, or use an editor plugin that rewrites in place.

Why did my flow-style mapping become block style?

The dumper emits block style by default because it is what almost every YAML config uses and it diffs cleanly line by line. The parsed data is identical — {name: X, value: Y} and the block form are the same mapping.

What does the error line and column refer to?

The first position where the parser could not continue, converted to one-based numbering to match your editor. YAML errors are usually indentation or a stray tab a line or two above the reported point.

Free & private — why use this YAML Formatter and Validator

The YAML Formatter and Validator runs 100% client-side in your browser. Your data is never uploaded to a server, no account is required, and the tool is completely free. It works offline once the page has loaded and is part of a growing collection of privacy-first developer utilities.

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