JSON to YAML

JSON and YAML

YAML is the format of choice for configuration that people edit: Kubernetes manifests, Docker Compose, CI pipelines and OpenAPI specs. It expresses the same data as JSON with indentation instead of braces and fewer quotes. In fact YAML 1.2 is a superset of JSON, so converting JSON to YAML never loses information.

The trap is implicit typing. In YAML, yes, no, on, off were booleans in version 1.1, 007 can become a number and an empty value is null. This converter quotes such strings so they stay strings in any YAML reader, a frequent cause of surprises like Norway's country code NO turning into false.

Worked example

{"service":"web","replicas":3,"ports":["80:80"],"debug":"no"}

becomes

service: web
replicas: 3
ports:
  - 80:80
debug: "no"

debug keeps its quotes because unquoted no is a boolean for YAML 1.1 tools.

The page parses the JSON strictly (invalid input is reported with line and column), then writes YAML 1.2 using block style: one key per line, list items with -, nesting by indentation of 2 or 4 spaces. Strings that a YAML parser might read as a boolean, null or number are wrapped in double quotes. Key order is preserved and long strings are never folded across lines. Use YAML to JSON for the reverse. Everything runs in this tab.