CodeItBro

YAML Validator

Validate and format YAML files online. Catch syntax errors, fix indentation, and ensure your configuration files are correct.

Common YAML Mistakes

  • • Indentation: YAML uses spaces, not tabs. Inconsistent indentation causes errors.
  • • Colons: Always add a space after colons in key-value pairs: key: value
  • • Special Characters: Strings with special characters (like : or #) should be quoted.
  • • Boolean gotchas: Words like yes, no, on, off are treated as booleans.

Validate YAML Configuration Files

YAML is the backbone of modern DevOps workflows. From Kubernetes manifests to CI/CD pipelines, a single syntax error can break deployments. Our validator helps you catch errors before they cause problems, with clear error messages pointing to the exact line.

YAML Validation

Why Use This Tool?

Instant Validation

Get immediate feedback on your YAML syntax with detailed error messages.

Auto-Format

Clean up messy YAML with consistent indentation and proper formatting.

100% Private

All processing happens locally. Your config files never leave your browser.

Syntax Highlighting

Edit with full syntax highlighting to catch errors as you type.

How this YAML Validator works

This YAML validator uses the js-yaml library to parse YAML content according to the YAML 1.1 specification. The parser constructs a complete document tree from the input, detecting syntax errors including indentation inconsistencies, missing colons, unclosed quotes, invalid characters, and structural problems that would prevent proper YAML interpretation.

Error messages include precise line numbers and descriptions extracted from the parser's diagnostic output, helping you quickly locate and fix issues. The formatter option serializes the parsed document back to YAML with consistent 2-space indentation and clean structure, useful for standardizing configuration files across teams or cleaning up manually edited YAML.

The tool handles common YAML features including nested objects, arrays, multi-line strings with block scalars, anchors and aliases, and complex key types. Processing runs entirely client-side in your browser, making it safe for validating sensitive configuration files containing database credentials, API secrets, or infrastructure settings. This is particularly valuable for DevOps workflows involving Kubernetes manifests, Docker Compose files, or CI/CD pipeline configurations.

How to Use

1

Enter YAML

Paste your YAML configuration or data into the editor.

2

Validate

Click Validate to check for syntax errors and structure issues.

3

Format

Optionally format your YAML for consistent indentation and style.

Example Usage

Detecting a missing colon in YAML:

Input
name: John age 30
Output
Error: Line 2: can not read an implicit mapping pair; a colon is missed

Frequently Asked Questions

What is YAML?
YAML (YAML Ain't Markup Language) is a human-readable data serialization format commonly used for configuration files in DevOps, Kubernetes, Docker, and more.
What errors does this validator catch?
It catches syntax errors like incorrect indentation, missing colons, invalid characters, unclosed quotes, and structural issues in your YAML.
Can I format my YAML?
Yes! Click the Format button to automatically reformat your YAML with consistent 2-space indentation and proper structure.
Is my data secure?
Absolutely. All validation happens in your browser. No data is sent to any server.

Related Tools

JSON Validator

Validate and debug JSON data.

YAML to JSON Converter

Convert YAML configuration files to JSON format instantly.

The YAML Validator is maintained by CodeItBro. We aim to provide the best free developer tools on the web. If you have feedback or suggestions, please visit our contact page.