YAML Formatter/Validator
Format and validate YAML data
YAML Formatter/Validator
Format, validate, and minify YAML data
About YAML Formatter
Format YAML with consistent indentation or minify to remove extra whitespace. YAML uses spaces (not tabs) for indentation.
Privacy & Security
All YAML formatting and validation happens entirely in your browser using JavaScript. Your configuration files are never uploaded to our servers, transmitted over the network, stored in databases, or logged anywhere. This is essential when working with YAML files containing secrets, API keys, database credentials, or infrastructure configurations. When you close the page, your YAML is permanently erased from browser memory. Completely private and secure for even the most sensitive configuration files.
About YAML Formatter
Format and validate YAML configuration files with our free online YAML formatter and validator. Whether you're a DevOps engineer managing Kubernetes manifests, a developer writing Docker Compose files, a CI/CD specialist configuring pipelines, or a system administrator maintaining Ansible playbooks, our tool instantly beautifies YAML, detects indentation errors, validates syntax, and helps you understand complex nested structures. Perfect for catching those frustrating whitespace issues that break YAML parsing and ensuring your configurations work correctly before deployment.
Key Features
Instant Formatting
Beautify YAML with correct indentation and spacing automatically in milliseconds
Syntax Validation
Detect YAML syntax errors, indentation problems, and structural issues instantly
Indentation Correction
Automatically fix inconsistent spacing and tab/space mixing for valid YAML
YAML to JSON Conversion
Convert YAML to JSON format and back for interoperability and debugging
Error Line Highlighting
Show exact line numbers and descriptions for syntax and indentation errors
Syntax Highlighting
Color-coded keys, values, comments, and data types for improved readability
Multi-Document Support
Handle YAML files with multiple documents separated by --- markers
Anchor & Alias Detection
Properly format YAML anchors (&) and aliases (*) for reusable configurations
Copy & Download
Copy formatted YAML to clipboard or download as .yml/.yaml file instantly
Large File Handling
Process complex Kubernetes manifests and large configuration files efficiently
How to Use the YAML Formatter
Paste YAML Content
Copy your YAML configuration file and paste it into the input text area
Choose Indentation
Select your preferred indentation (2-space is standard for most YAML configs)
Format & Validate
Click 'Format' to beautify YAML and automatically validate syntax for errors
Copy or Convert
Copy formatted YAML to clipboard, download as file, or convert to JSON if needed
Frequently Asked Questions
What is YAML and why is proper formatting important?
YAML (YAML Ain't Markup Language) is a human-readable data serialization format used for configuration files. Unlike JSON or XML, YAML relies entirely on indentation and whitespace to define structure - even a single misplaced space can cause parsing errors and broken deployments. Proper formatting is critical because YAML parsers are very strict about indentation, making formatting essential for working configurations.
Why does YAML fail with 'mapping values are not allowed here'?
This common error usually means there's an indentation problem or a missing colon after a key. YAML requires consistent indentation (typically 2 spaces per level) and doesn't allow tabs. Our formatter automatically detects these issues and shows you the exact line number where the indentation is incorrect, making it easy to fix structural problems.
Can this tool convert between YAML and JSON?
Yes! The formatter includes bidirectional YAML ⡠JSON conversion. This is useful for debugging, comparing configurations, or working with tools that only accept JSON. The conversion preserves data structure, arrays, nested objects, and data types accurately.
Does it support advanced YAML features like anchors and aliases?
Absolutely! The formatter fully supports YAML anchors (&) for defining reusable content and aliases (*) for referencing it, which are commonly used in Kubernetes and Docker Compose files to avoid repetition. It also handles multi-document YAML files, merge keys (<<), and complex nested structures.
Can I validate Kubernetes YAML files?
Yes! While this tool validates YAML syntax and structure, it checks that your file is valid YAML. For Kubernetes-specific validation (checking if resources match the schema), you'd need a Kubernetes-specific validator. However, most Kubernetes deployment failures are due to YAML syntax errors, which this tool catches perfectly.
Is this YAML formatter free?
Yes! Our YAML formatter is completely free to use with unlimited formatting and validation, no registration required.
Will my configuration files be stored or uploaded?
No. All YAML processing happens entirely in your browser using JavaScript. Your configuration files are never uploaded to our servers, stored in databases, logged, or transmitted anywhere. This is crucial when working with YAML files containing API keys, passwords, or sensitive infrastructure configurations. Completely private and secure.
Does it work on mobile devices?
Yes! The YAML formatter is fully responsive and works on smartphones and tablets for quick validation and formatting on the go.
Common Use Cases
- Kubernetes Manifests: Format and validate Kubernetes deployment, service, and ingress YAML files
- Docker Compose Files: Beautify docker-compose.yml files and catch indentation errors before deployment
- CI/CD Pipeline Config: Format GitHub Actions, GitLab CI, CircleCI, and Jenkins pipeline YAML files
- Ansible Playbooks: Validate Ansible playbook syntax and format task definitions with proper spacing
- OpenAPI Specifications: Format Swagger/OpenAPI YAML files for API documentation and validation
- Configuration Management: Beautify application config files, settings, and environment variable definitions
- Helm Charts: Format Helm values.yaml files and Kubernetes chart templates for clarity
- CloudFormation Templates: Format AWS CloudFormation YAML templates for infrastructure as code
Why Use Our YAML Formatter?
Hunting for that single misplaced space breaking your entire Kubernetes deployment or Docker Compose file is frustrating and time-consuming. YAML's strict indentation requirements make it easy to introduce errors that are hard to spot visually. Our free YAML formatter instantly identifies indentation problems, validates syntax, and beautifies your configurations with proper spacing, eliminating hours of debugging. Whether you're deploying to production, writing CI/CD pipelines, or managing infrastructure as code, you need confidence that your YAML is correct before running it. No more guessing if you used spaces or tabs, or manually counting indentation levels - just paste, validate, and deploy with confidence.