YAML/JSON Validator & Converter
Validate, format, and convert between YAML and JSON. Client-side processing — your data never leaves your browser.
Document Statistics
YAML Syntax Reference
Quick reference for YAML 1.2 syntax. YAML is a superset of JSON, so valid JSON is also valid YAML.
| Syntax | Description | Example |
|---|---|---|
key: value | Key-value pair (mapping) | name: John |
- item | List item (sequence) | - apple\n- banana |
| | Literal block scalar (preserves newlines) | text: |\n line1\n line2 |
> | Folded block scalar (joins lines) | text: >\n long\n text |
&anchor | Define an anchor | defaults: &defaults\n timeout: 30 |
*alias | Reference an anchor | production:\n <<: *defaults |
# comment | Comment (ignored) | # This is a comment |
--- | Document start marker | ---\ndoc1\n---\ndoc2 |
... | Document end marker | data: value\n... |
null / ~ | Null value | empty: null |
true / false | Boolean values | enabled: true |
'string' | Single-quoted string (literal) | path: 'C:\\path' |
"string" | Double-quoted string (escapes) | msg: "Hello\\nWorld" |
Common YAML Errors & How to Fix Them
Tab Characters
YAML requires spaces for indentation, not tabs
Fix: Replace all tabs with spaces (typically 2 spaces per level)
Missing Colon
Keys must be followed by a colon and space
Fix: Add a colon after the key name: key: value
Inconsistent Indentation
All items at the same level must have identical indentation
Fix: Use consistent 2-space indentation throughout
Unquoted Special Characters
Values with special characters need quotes
Fix: Wrap values containing : @ # & * in quotes
Duplicate Keys
Each key must be unique within its mapping
Fix: Rename or remove the duplicate key
Invalid Anchor/Alias
Anchors (&) and aliases (*) must reference valid nodes
Fix: Ensure anchor is defined before alias reference
Frequently Asked Questions
How do I validate YAML online?
Paste your YAML content into the input editor. The validator automatically detects YAML format and validates it against the YAML 1.2 specification. Any syntax errors will be displayed with line numbers and helpful suggestions for fixing them.
How do I convert YAML to JSON?
Paste your YAML content and click the "Convert to JSON" button. The tool parses your YAML according to the YAML 1.2 spec and outputs valid JSON following RFC 8259. You can then copy or download the result.
How do I convert JSON to YAML?
Paste your JSON content and click the "Convert to YAML" button. The tool validates your JSON against RFC 8259 and converts it to clean, properly indented YAML 1.2 format.
What causes YAML syntax errors?
Common YAML errors include: incorrect indentation (YAML uses spaces, not tabs), missing colons after keys, unquoted special characters, improper list formatting, and duplicate keys. Our validator shows the exact line and column where errors occur.
Is my data secure when using this validator?
Yes, absolutely. All validation and conversion happens entirely in your browser using JavaScript. Your data never leaves your device and is never sent to any server. This is a 100% client-side tool. You can verify this by checking your browser's network tab — no data is transmitted.
What YAML version does this validator support?
This validator supports YAML 1.2, the latest stable version of the YAML specification. It handles all standard YAML features including anchors, aliases, multi-line strings, block scalars, and complex nested structures.
Can I validate Kubernetes YAML files?
Yes! This tool validates the YAML syntax of Kubernetes manifests, Helm charts, Docker Compose files, GitHub Actions workflows, Ansible playbooks, and any other YAML-based configuration files. It checks for valid YAML structure (syntax validation) but not Kubernetes-specific schema validation.
What is the difference between YAML and JSON?
YAML and JSON are both data serialization formats. Key differences:
- Readability: YAML uses indentation and is more human-readable; JSON uses braces/brackets
- Comments: YAML supports comments (#); JSON does not
- Data types: YAML supports more types (dates, timestamps, etc.)
- Compatibility: Valid JSON is valid YAML (YAML is a superset)
- Use cases: YAML for config files; JSON for APIs and data exchange
What JSON standard does this tool follow?
This tool follows RFC 8259 (The JavaScript Object Notation Data Interchange Format), which is the current standard for JSON. It properly handles Unicode characters, escape sequences, number formats, and structural validation.