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The YAML validator helps you validate YAML syntax, format YAML documents, and convert between YAML and JSON formats. It provides real-time validation with auto-detection of errors.

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Features

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Validation

Check if your YAML is syntactically correct:
  • Real-time validation as you type
  • Detailed error messages with line information
  • Visual indicators for valid/invalid YAML
  • Line count and file size statistics
The validator automatically checks syntax as you type, with a 500ms delay to avoid performance issues.

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Formatting

Format YAML with consistent indentation:
  • 2-space indentation (standard)
  • 120-character line width
  • Consistent structure and spacing
  • Removes unnecessary complexity

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YAML to JSON conversion

Convert YAML to JSON format:
  • Automatic conversion when validation succeeds
  • Pretty-printed JSON output
  • Useful for debugging and data transformation
  • Bidirectional conversion support

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JSON to YAML conversion

Convert JSON back to YAML:
  • Edit the JSON output
  • Click “Convert to YAML” to transform back
  • Useful for format transformation
  • Preserves data structure

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Use cases

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Configuration files

Validate Kubernetes, Docker Compose, and other YAML configs: 
server:
  host: localhost
  port: 8080
  ssl:
    enabled: true
    certificate: /path/to/cert.pem

database:
  type: postgresql
  host: db.example.com
  port: 5432
  name: myapp

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CI/CD pipelines

Check GitHub Actions, GitLab CI, or CircleCI configuration files.

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Data serialization

Convert between YAML and JSON for data processing: 
features:
  - authentication
  - logging
  - monitoring
  - caching

settings:
  debug: false
  max_connections: 100
  timeout: 30s

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API specifications

Validate OpenAPI/Swagger YAML specifications.

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YAML syntax guide

The validator includes helpful syntax tips:
  • Indentation - Use 2 spaces (no tabs)
  • Strings - Strings with special characters need quotes
  • Lists - Use dashes (-) or square brackets []
  • Objects - Use colons (:) or curly braces
  • Comments - Start with # symbol
YAML is whitespace-sensitive. Always use spaces for indentation, never tabs.

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Validation feedback

The validator provides clear visual feedback:
  • Valid badge - Green checkmark when YAML is valid
  • Invalid badge - Red X when YAML has errors
  • Stats badge - Shows line count and byte size
  • Error alerts - Detailed error messages with descriptions

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Examples

Click the “Examples” button to load a sample YAML configuration: 
# Example YAML configuration
server:
  host: localhost
  port: 8080
  ssl:
    enabled: true
    certificate: /path/to/cert.pem

database:
  type: postgresql
  host: db.example.com
  port: 5432
  name: myapp
  credentials:
    username: user
    password: secret

features:
  - authentication
  - logging
  - monitoring
  - caching

settings:
  debug: false
  max_connections: 100
  timeout: 30s

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Copy functionality

Each section has a copy button:
  • Copy YAML - Copy the YAML input
  • Copy JSON - Copy the JSON output
  • Click the copy icon in the top-right of each editor

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Keyboard shortcuts

  • Cmd/Ctrl + Enter - Validate YAML
  • Cmd/Ctrl + K - Clear all inputs
  • Cmd/Ctrl + C - Copy output

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Tips

Use the format button to automatically fix indentation issues in your YAML.
The JSON output is useful for debugging - it shows exactly how the YAML parser interprets your document.
Comments in YAML are preserved during formatting but removed during JSON conversion.

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Common errors

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Indentation errors

YAML requires consistent indentation. Mixing spaces and tabs causes errors.

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Unquoted special characters

Strings containing colons, brackets, or other special characters need quotes: 
# Incorrect
title: Hello: World

# Correct
title: "Hello: World"

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Invalid list syntax

Lists must have consistent formatting: 
# Correct
features:
  - feature1
  - feature2

# Also correct
features: [feature1, feature2]

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