DataFormattools
YAML · Validator

YAML Validator & Syntax Checker

Validate YAML syntax online with instant line-by-line error detection. Check YAML validity, lint configuration files, and spot indentation bugs.

Syntax & Structure Validator
Paste or type data below to validate syntax and structure in real time.
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100% In-Browser Privacy: All conversions, formatting, and validations run purely on your machine using client-side JavaScript. Your data, code snippets, and environment variables are never transmitted to any server or recorded in logs.
Specifications

How YAML Validator Works

  • Parses YAML syntax against YAML 1.2 grammar.
  • Reports exact line and column positions for syntax violations.
  • Calculates key count and nesting depth.
Demonstration

Example Input & Output

Validates YAML syntax, checking mapping alignments, sequence indentation, and literal values.

YAML Code
name: web-service
replicas: 3
image: nginx:latest
env:
  - name: NODE_ENV
    value: production
  - name: PORT
    value: "3000"
Expected Output
✓ Valid YAML (YAML 1.2 Standard)
Applications

Common Use Cases

Docker Compose Verification

Validate docker-compose.yml files before running container stacks.

Ansible Playbook Checks

Catch indentation and syntax errors in Ansible playbooks.

Guidelines

Key Specifications & Gotchas

Missing Space After Colon

A colon must be followed by a space (key: value), not key:value.

Unescaped Colons in Values

Strings containing colons must be enclosed in quotes.

Questions

Frequently Asked Questions

How do I check if my YAML file is valid?

Paste your YAML document into the validator; any syntax or indentation errors are flagged immediately.

What are the most common YAML syntax errors?

The most frequent errors are using tab characters, inconsistent indentation, and omitting the space after colons.

Does this linter support multi-document YAML?

Yes, documents separated by --- are supported.

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