Input YAML
Validation Results
YAML Validator
Check YAML syntax and detect indentation errors instantly
What This Tool Does
This YAML validator checks your YAML files for syntax errors before you use them in production. It examines indentation patterns, key-value pairs, list structures, and common formatting issues that cause YAML parsers to fail.
The validation happens in your browser. When you paste YAML content or upload a file, it analyzes the structure without sending data to any server. You'll see specific error messages pointing to lines that need fixing.
Who Needs This
DevOps engineers working with Kubernetes manifests, Docker Compose files, or Ansible playbooks use this to catch syntax errors before deployment. A single indentation mistake in a YAML file can break an entire deployment pipeline.
Software developers who write configuration files for applications often need to verify YAML structure. Many frameworks like Spring Boot, Rails, and Django use YAML for configuration, and this tool helps catch errors early.
System administrators managing CI/CD pipelines with tools like GitHub Actions, GitLab CI, or CircleCI can validate their workflow files before committing changes.
Key Features
Indentation Checking
Detects inconsistent spacing and validates that your YAML uses spaces consistently. YAML requires spaces, not tabs, for indentation.
Key-Value Validation
Checks that key-value pairs follow proper YAML format with correct colon placement and spacing requirements.
List Format Checking
Validates list syntax including dash placement and proper indentation for nested list items.
Error Line Numbers
Shows exactly which line contains errors so you can fix problems quickly without searching through the entire file.
File Upload Support
Load YAML files directly from your computer. Works with .yaml, .yml, and text files containing YAML content.
Client-Side Processing
All validation runs in your browser. Your YAML files stay on your device, which matters for configuration files containing sensitive data.
Common YAML Errors
When validation fails, here are the issues you'll typically encounter:
Tab Characters: YAML does not allow tabs for indentation. If you copied YAML from an editor that uses tabs, you'll need to convert them to spaces. Most YAML parsers require 2 spaces per indentation level.
Inconsistent Indentation: Each level of nesting must use the same number of spaces throughout the document. Mixing 2-space and 4-space indentation causes parsing failures.
Missing Colons: Key-value pairs require a colon followed by a space. Writing "key:value" without a space after the colon is invalid. The correct format is "key: value".
Incorrect List Format: List items start with a dash followed by a space. The dash must align with the parent key's indentation, and the list content must be indented further.
Unquoted Special Characters: Values containing colons, brackets, or certain special characters need quotes. For example, "time: 12:00" should be "time: '12:00'" to prevent the colon from being interpreted as a nested key.
Incorrect Multi-line Values: Multi-line strings require specific formatting using the pipe (|) or greater-than (>) characters. Simply breaking a value across lines without these indicators causes errors.
Privacy and Security
This validator runs entirely in your web browser using JavaScript. When you upload a YAML file or paste content, nothing is transmitted to any server. All validation happens locally on your device.
This is important for configuration files that may contain database credentials, API keys, or internal infrastructure details. Since processing is client-side, there's no risk of exposing sensitive information through network transmission.
The tool doesn't cache your input or save files to browser storage. When you close the tab, all data is cleared from memory.
Common Questions
YAML uses indentation to show structure and relationships, similar to Python. The number of spaces determines nesting levels, so inconsistent spacing breaks the document's hierarchy. This makes YAML human-readable but sensitive to indentation errors.
No. The tool identifies errors and tells you where they are, but it cannot automatically repair structural issues. YAML formatting is context-dependent, and automatically fixing indentation could change the intended meaning of your configuration.
No. All validation happens in your browser. The YAML content stays on your device and is never transmitted anywhere.
YAML is a superset of JSON designed to be more human-readable. It uses indentation instead of brackets and supports features like comments and multi-line strings. JSON is stricter and more widely supported, while YAML is easier to read and write by hand.
Hidden characters like tabs often cause this. Your editor may display tabs and spaces identically, but YAML only accepts spaces. Try showing invisible characters in your editor or copy-paste the YAML into a plain text editor to check.
This tool validates YAML structure only. It checks syntax and formatting but doesn't verify Kubernetes-specific requirements like required fields, valid apiVersions, or resource schemas. You'll need kubectl or a Kubernetes-specific validator for schema validation.