JSON ↔ YAML Converter & Validator
Convert between JSON and YAML instantly, or validate YAML syntax with line-level error reporting. Supports Docker Compose, Kubernetes, GitHub Actions, and any YAML-based config. Runs entirely in your browser — nothing is uploaded.
JSON vs YAML — Key Differences
| Feature | JSON | YAML |
|---|---|---|
| Syntax | Braces & quotes required | Indentation-based, minimal punctuation |
| Comments | Not supported | Supported (#) |
| Data types | string, number, bool, null, array, object | Same + timestamps, anchors, aliases |
| Readability | Verbose for nested data | Very human-readable |
| Strictness | Strict | Permissive (can be error-prone) |
| Common use | APIs, REST, JavaScript configs | Docker, K8s, CI/CD, Ansible |
Common Use Cases
- Kubernetes: Manifests (Deployment, Service, ConfigMap) are written in YAML. Use this tool to quickly verify structure or convert a JSON API response back to manifest form.
- Docker Compose:
docker-compose.ymluses YAML. Convert from JSON test data or validate your compose file beforedocker compose up. - GitHub / GitLab Actions: CI/CD pipeline files are YAML. The validator catches indentation errors that would fail your pipeline.
- Ansible playbooks: All playbooks are YAML — validate before running to catch syntax errors early.
- OpenAPI / Swagger: API specs can be written in either JSON or YAML — convert between them freely.
YAML Gotchas to Watch Out For
- Indentation matters: YAML uses spaces (not tabs) for indentation. Mixing them causes parse errors.
- Implicit typing:
yes,no,on,offare parsed as booleans in YAML 1.1. Quote them if you need string values. - Colons in strings: A colon followed by a space (
:) starts a mapping entry. Always quote strings that contain colons. - Multi-line strings: Use
|(literal block) or>(folded block) to embed multi-line text cleanly.
Frequently Asked Questions
Is YAML a superset of JSON?
YAML 1.2 is a strict superset of JSON — every valid JSON document is also valid YAML. However, YAML 1.1 (used by many older parsers) has some differences in how it handles special values like true, false, and octal numbers.
Does this handle multi-document YAML?
The converter handles single YAML documents. Multi-document files (separated by ---) will parse only the first document. The validator will detect syntax errors in any document.
Is my data safe?
All conversion and validation happens entirely in your browser using the js-yaml library. No data is sent to any server.