YAML to JSON Converter

How it works

YAML to JSON runs a small recursive-descent parser written for this page. It first strips comments (carefully, so a # inside a quoted string survives), records each line's indentation, then builds the structure the way YAML defines it: indentation opens nested maps, lines starting with - build sequences, and everything else is a scalar. Scalars are typed by the same rules real YAML parsers use: true/false become booleans, ~ and null become null, bare numbers become numbers, quoted strings stay strings, and inline [a, b] or {k: v} flow syntax is handled too. The result is serialized with JSON.stringify at your chosen indent. JSON to YAML is the reverse: JSON.parse validates the input, then an emitter walks the value and writes indented YAML, quoting any string that would otherwise be misread as a number, boolean, or null.

One deliberate choice worth knowing about: this parser only treats literal true and false as booleans. Older YAML 1.1 parsers also convert yes, no, on, and off, which is how Norway's country code NO famously becomes false in config files (the "Norway problem"). Here it stays the string it looks like.

It is a subset parser, kept small on purpose: anchors and aliases (&/*), multi-document files, and block scalars (| and >) aren't supported, so a complex Kubernetes manifest using those features won't round-trip. For everyday config conversion it covers what you actually paste.

Conversion happens entirely in your tab on every keystroke. No parser service is called: DevTools' Network panel stays silent while you type, so config files full of hostnames and secrets never leave your machine.