YAML has become the go-to format for configuration files — from Docker Compose and Kubernetes to CI pipelines and application settings. But sometimes you need that data as JSON instead, or you simply want to check that your YAML is valid. Our free YAML formatter validates YAML and converts between YAML and JSON instantly in your browser.
YAML vs JSON: What's the Difference?
YAML (YAML Ain't Markup Language) and JSON (JavaScript Object Notation) can represent the same data, but they look very different:
- YAML uses indentation and is designed to be human-friendly. It avoids brackets and quotes where possible, which makes config files clean and readable.
- JSON uses braces, brackets, and quotes. It is more verbose but is the native format for web APIs and is parsed by virtually every programming language.
Because they are structurally equivalent, any valid YAML can be converted to JSON and back without losing information.
How to Convert YAML to JSON Online
- Paste your YAML into the input box.
- Choose Convert to JSON (or the reverse direction).
- View the converted output, properly formatted.
- Validate to confirm your YAML has no syntax errors.
- Copy the result with one click.
Everything runs locally in your browser, so your configuration data never leaves your device.
Why Convert Between YAML and JSON?
Working with APIs — Many tools accept JSON but you author configuration in YAML; converting bridges the gap.
Debugging config files — Converting YAML to JSON makes its exact structure explicit, which helps you spot a misplaced key or wrong nesting level.
Migration — Move settings between systems that expect different formats.
Common YAML Mistakes
YAML's reliance on indentation makes it powerful but error-prone. Watch out for:
- Inconsistent indentation — YAML requires spaces, never tabs, and the indentation level defines the structure.
- Missing spaces after colons —
key:valueis wrong; it must bekey: value. - Unquoted special characters — values containing colons or other symbols may need quotes.
A validator catches these instantly, saving you from confusing runtime errors.
Frequently Asked Questions
Is the YAML formatter free? Yes — it is free, requires no sign-up, and runs entirely in your browser.
Can it convert JSON back to YAML? Yes. The tool converts in both directions — YAML to JSON and JSON to YAML.
Does it validate YAML? Yes. It checks your YAML for syntax errors like bad indentation or missing spaces and reports them.
Is my data uploaded anywhere? No. All conversion and validation happens locally in your browser.
Need your config as JSON, or just want to check it is valid? Paste your YAML and convert it in seconds.