What is a YAML Formatter?
A YAML formatter validates and beautifies YAML code, ensuring consistent 2-space indentation and proper structure. It also converts YAML to JSON to help you verify how the data will be parsed. This is essential when working with CI/CD pipelines, Kubernetes manifests, Docker Compose files, Ansible playbooks, and any application configuration files that use YAML syntax.
How to Use the YAML Formatter
Paste your YAML into the input panel. Click "Format YAML" to normalize indentation. Click "Validate" to check structure without reformatting. Click "To JSON" to see the parsed output as JSON. If there are syntax errors, a red bar shows the exact line and character position. All processing happens locally in your browser — no data leaves your device.
How the YAML Formatter Works
The formatter uses js-yaml (version 4.1.0), the most widely used JavaScript YAML parser. It parses the YAML into a JavaScript object (catching any syntax errors), then serializes it back to YAML with consistent 2-space indentation and block-style formatting. For JSON conversion, it uses JSON.stringify with 2-space indentation.
Benefits of Using a YAML Formatter
- Catches indentation errors before they cause CI/CD pipeline failures
- Normalizes YAML style for consistency across team members
- JSON conversion shows exactly how your YAML will be parsed
- 100% client-side — safe for Kubernetes secrets and CI/CD credentials
- Real-time validation as you type
Frequently Asked Questions
What is YAML and where is it used?
YAML is a human-readable data format used for configuration files. Common uses: GitHub Actions, Docker Compose, Kubernetes manifests, Ansible, GitLab CI, Helm charts, and Rails database.yml. YAML is preferred for configs because it supports comments and is more readable than JSON.
What are common YAML syntax errors?
Incorrect indentation (tabs not allowed — only spaces), missing colon after key, unquoted strings with special characters, mixed indentation levels. The formatter reports exact line and column of errors.
What is the difference between YAML and JSON?
YAML is a superset of JSON (all valid JSON is valid YAML). YAML adds: comments, more readable syntax, multiline strings, anchors/aliases. JSON is standard for APIs (universal parser support). YAML is standard for config files. Use our JSON Formatter for JSON.
Can I use tabs in YAML?
No. YAML strictly prohibits tab characters for indentation — only spaces. This is the most common cause of YAML errors. Configure your editor to use spaces (typically 2 or 4).
How do I write a multiline string in YAML?
Literal block (|): preserves newlines. Folded block (>): folds newlines to spaces (except blank line separators). Example: description: | line one\n line two
What is the difference between YAML anchors and aliases?
Anchor (&name) defines reusable values. Alias (*name) references them. Used for DRY config: define shared settings once, inherit elsewhere with <<: *anchor.
Is my YAML data private when using this formatter?
Yes. All processing happens in your browser using js-yaml (loaded once from jsDelivr CDN). Your YAML content is never sent to any server. Safe for Kubernetes secrets and CI/CD credentials.
How do I convert YAML to JSON?
Click the "To JSON" button. The formatter parses your YAML and outputs formatted JSON. Useful for verifying your YAML parses correctly, or for converting configs to API-compatible JSON format.