YAML Formatter & Validator

YAML Formatter & Validator

YAML is human-friendly, but it’s also easy to break: a single wrong indent, a missing : or a stray tab can invalidate the entire file.

This tool helps you validate, format, and standardize YAML safely and quickly—right in the browser.

What you can do

• Validate YAML with clear error feedback (including line/column).
• Format YAML into clean, consistent indentation.
• Sort keys to create stable diffs and consistent config style.
• Convert YAML → JSON for APIs, debugging, and tooling.
• Copy / Download results instantly.

Workflow & Usage

1. Paste or drop YAML into the left editor.

   • Supports .yml and .yaml files.

2. Choose output format:

   • YAML → validate + pretty format.
   • JSON → convert YAML to JSON (pretty or minified).

3. Adjust options:

   • Indent → 2 or 4 spaces (YAML and pretty JSON).
   • Sort keys → stable output for version control.
   • Minify → compact one-line JSON (only in JSON mode).

4. Copy or Download:

   • Hover the right editor to reveal Copy.
   • Use Download to save the result.

Under each editor you’ll see size in bytes and line counts so you can quickly compare before/after.

Common YAML Pitfalls (and how to avoid them)

Indentation and tabs

• YAML indentation must be spaces (tabs often break parsing).
• Keep indentation consistent—2 spaces is common; 4 is fine if your repo uses it.

Colons and quoting

• Keys are written as key: value.

• Quote values when they could be misread:

  • yes/no/on/off may be treated as booleans in some YAML interpretations.
  • 0123 may be treated differently depending on the parser.

Lists

• Lists start with -:

ports:
  - 80
  - 443

Multi-line strings

Use block scalars:

description: |
  Line one
  Line two

Use Cases

Kubernetes manifests

Format and validate manifests before applying:

• Deployment, Service, Ingress
• Helm-generated values.yaml

GitHub Actions / CI configs

Make workflow YAML readable and consistent:

• .github/workflows/*.yml
• CI pipelines (GitLab CI, CircleCI configs)

Docker Compose

Clean up Compose files and spot errors fast:

• docker-compose.yml
• multi-service stacks with volumes and networks

App & infra configuration

Standardize configuration files across environments:

• config.yml
• feature flags and settings
• secrets templates (avoid pasting real secrets into public places)

Tips for Clean, Stable Diffs

• Turn on Sort keys before committing to keep diffs predictable.
• Keep indentation consistent across the repo (choose 2 or 4 and stick to it).
• Convert to JSON when debugging what YAML actually means (useful for spotting accidental types).