YAML Formatter & Validator
Format, validate, beautify, and convert YAML documents and manifests online. Supports multi-document YAML (---), line/column diagnostics, 100% client-side.
| Feature | YAML | JSON |
|---|---|---|
| Syntax Style | Indentation-based (whitespace) | Braces `{}` & Brackets `[]` |
| Comments Support | Supported (`#`) | Not Supported |
| Human Readability | High (Config files / K8s) | Machine API Oriented |
| Multi-Document | Supported (`---`) | Single document root |
Use | to keep newlines (Literal block) or > to fold newlines into spaces (Folded block).
Define reusable blocks with &anchorName and reference them with *anchorName to eliminate duplication.
What Is YAML?
YAML is a human-readable data format that uses indentation instead of brackets and braces, commonly used for configuration files — Kubernetes manifests, Docker Compose, CI pipelines, and OpenAPI specs are all typically written in YAML.
How to Use the YAML Formatter & Validator
- Paste YAML to format, validate, or convert it.
- Formatting normalizes indentation and structure; validation checks the syntax and reports the exact line of any error.
- Convert to or from JSON when you need to move data between the two formats.
- Multi-document YAML (separated by ---) is supported.
Technical Notes
- YAML is indentation-sensitive — mixing tabs and spaces, or inconsistent indentation, is one of the most common sources of parsing errors.
- Because YAML is a superset of JSON's data model in most implementations, JSON documents are typically also valid YAML, which makes JSON ↔ YAML conversion straightforward in the common case.
Frequently Asked Questions
Do comments survive YAML formatting?+
When parsing YAML into object structures, standard parsers discard comments (#). Therefore, converting YAML → JSON or re-formatting parsed YAML will strip comments.
How does multi-document YAML (---) work in JSON conversion?+
When multiple YAML documents separated by --- are converted to JSON, the engine packages them as an array of JSON objects so no document data is lost.