Does it preserve comments?

Conversion uses the data model, so YAML comments are not carried into JSON (JSON has no comments).

What if my input is invalid?

You get a clear parse error for whichever format you're converting from.

No. Conversion runs entirely on your device.

Convert YAML to JSON and JSON to YAML in either direction. Runs entirely in your browser — no uploads, no sign-up.

Convert between YAML and JSON in either direction, so you can move config between formats without manual rewriting.