YAML syntax checker

YAML Validator

Validate YAML code online and find common syntax problems. Check indentation, tabs, missing colons, duplicate keys, brackets, quotes, errors, and warnings.

Syntax Check Line Warnings Download Report

Find YAML issues fast

Useful for Docker Compose, Kubernetes, GitHub Actions, CI/CD configs, app settings, and API documentation.

Free YAML Validator Tool

Paste YAML code and check it for common syntax errors, warnings, and indentation issues.

Input YAML

YAML Code Paste YAML config, Docker Compose, Kubernetes, GitHub Actions, or API YAML here.

This browser-based validator checks common YAML problems. For mission-critical deployment files, also validate inside your actual YAML parser or CI tool.

Validation Result

Ready to Validate

Paste YAML code and click validate to check syntax, indentation, tabs, brackets, and common YAML issues.

0 Total Lines

0 Errors

0 Warnings

Ready Status

YAML Validation Report

Type	Line	Message	Fix Suggestion
Validation report will appear here.

Quick YAML Examples

YAML is indentation-sensitive. One wrong space or tab can break Docker, Kubernetes, GitHub Actions, and other config files.

Why Use a YAML Validator?

A YAML Validator helps you find syntax mistakes before your configuration file breaks a build, deployment, or application.

Check YAML Syntax

Find common YAML problems like tabs, invalid indentation, missing colons, duplicate keys, and unbalanced brackets.

Line Based Report

See errors and warnings with line numbers so you can quickly locate and fix the issue.

Copy and Download

Copy the validation report or download it as a text file for debugging, documentation, or client work.

What Is YAML Validation?

YAML validation checks whether a YAML file follows correct structure and readable formatting rules. YAML is widely used for configuration files because it is clean and human-readable, but it is also sensitive to indentation.

A validator helps catch common mistakes before the YAML file is used in Docker Compose, Kubernetes, GitHub Actions, CI/CD pipelines, API docs, or application settings.

Issue	Meaning	Common Fix
Tabs	YAML should use spaces, not tabs	Replace tabs with spaces
Bad Indentation	Nested structure may be wrong	Use consistent 2 or 4 spaces
Missing Colon	Key-value separator may be missing	Add colon after the key
Duplicate Keys	Same key appears at same level	Rename or remove duplicate key
Unbalanced Brackets	Inline arrays or objects may be broken	Close brackets correctly

How It Works

Validate YAML code in three simple steps.

Paste YAML

Add YAML code from Docker, Kubernetes, GitHub Actions, CI/CD, app configs, or API documentation.

Run Validator

The tool checks common YAML syntax problems, indentation issues, tabs, duplicate keys, and brackets.

Fix Issues

Review the report, fix line-based errors, copy the report, or download it for later review.

YAML Validator FAQs

Common questions about YAML syntax, indentation, validation, and configuration files.

A YAML Validator checks YAML code for common syntax issues such as tabs, bad indentation, missing colons, duplicate keys, and bracket problems.

YAML uses indentation to define nesting and structure. A wrong space level can change the meaning or break the file.

YAML should use spaces. Tabs commonly cause parsing errors in YAML files.

No. The validation runs in your browser using JavaScript. It does not upload your YAML to any API or database.

No. It works with normal PHP and JavaScript. No API, database, cURL, or Composer package is required.