Developer Tools

YAML Formatter

Format, beautify, and validate YAML in your browser. Normalize indentation, sort keys, fix quotes, and catch syntax errors with line numbers.

Mode

Format or validate YAML

Indent

Quote style

Keys

Sort keys A-Z

YAML input

Up to 600,000 characters. Formatting and validation run entirely in your browser, so nothing is uploaded.

Formatted YAML

Formatted1 document27 keys472 B95 B smaller

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-app
  labels:
    app: web
    tier: frontend
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: web
        image: nginx:1.27
        ports:
        - containerPort: 80
        env:
        - name: NODE_ENV
          value: production
        - name: API_URL
          value: https://api.example.com

What the formatter cleans up

Indentation is normalized to your chosen step (2 or 4 spaces). Tabs in leading indent are rejected per the YAML spec.
Trailing whitespace after values and on otherwise-blank lines is removed.
Flow collections like [80,443] and {region: us-east-1,port:443} are expanded back to clean block style.
Quote style is normalized. Auto picks single quotes when possible (no escapes needed) and double quotes for strings that contain newlines or quotes.
Anchors and aliases are inlined on output, so the formatted result has no & / * references and is safe to diff.
Comments are stripped because the AST does not preserve them. Use Validate mode if you need to keep comments intact.

What the validator catches

Tabs used for leading indentation (a frequent cause of silent parser failures in CI pipelines).
Misaligned mapping keys, missing :, empty keys, and keys with unbalanced quoting.
Unclosed flow collections ([, {) and unterminated quoted strings.
Invalid escape sequences in double-quoted strings (\x, \u, \U).
Unknown aliases (*name) that have no matching &name anchor.

How to use

Paste your YAML into the input on the left, or click Load sample to see a worked Kubernetes example.
Pick a mode. Format rewrites the YAML with normalized indent, quotes, and key order. Validate only checks syntax.
In Format mode, choose 2 or 4 space indent, pick a quote style (Auto, Single, or Double), and optionally enable Sort keys A-Z.
Read the result on the right with byte stats and a clear error if the YAML cannot be parsed.
Click Copy YAML to put the formatted result on your clipboard, ready to paste back into your editor or commit.

About this tool

YAML Formatter cleans up and validates YAML configuration files entirely in your browser. Paste a Kubernetes manifest, GitHub Actions workflow, GitLab CI pipeline, Docker Compose file, Ansible playbook, OpenAPI spec, or any application config, and the tool re-emits a tidy version with consistent indentation, normalized quotes, and (optionally) keys sorted alphabetically. The parser handles the YAML 1.2 core schema subset that real config files use: block mappings and sequences, plain and quoted scalars (single and double, with full escape support), flow-style collections like [a, b, c] and {k: v}, literal | and folded > block scalars with all three chomping indicators, document separators (--- and ...), trailing # comments, and anchors and aliases (which are inlined on output so the formatted result is self-contained and safe to diff). Choose between 2-space and 4-space indent to match your team's style, pick a quote mode (Auto, Single, or Double) to enforce a consistent string representation, and toggle Sort keys A-Z when you need a deterministic ordering for code review or for canonicalising config that lives in version control. Validate mode parses without rewriting, so it is the right choice when you want to keep comments and original key order intact and just confirm the syntax is correct. Errors include 1-based line and column numbers along with a concise message: tab in leading indent, misaligned mapping keys, unclosed flow collections, unterminated quoted strings, invalid escape sequences, and unknown aliases are all surfaced clearly. The output panel shows live byte counts and how much smaller (or larger) the formatted version is, so you can confirm a cleanup pass was worth it. Useful for fixing the indentation drift that breaks Kubernetes apply, normalizing GitHub Actions and GitLab CI files before committing, cleaning up Ansible playbooks that were edited in different editors, prepping OpenAPI specs for review, and removing the trailing whitespace and stray blank lines that make diffs noisy. Parsing, validation, and emission run locally on your device, so the configs you paste here never leave your browser.

Free to use. Works in your browser. No signup, no login.

Related tools

YAML Formatter

How to use

About this tool

You may also like

YAML to JSON Converter

JSON to YAML Converter

JSON Formatter

JSON Lines Formatter

TOML to JSON Converter

JSON Tree Viewer