JSON to YAML

Convert JSON to YAML. One-way only — parsing YAML has too many traps (indentation, anchors, implicit typing) to do it half-heartedly.

Notes

JSON → YAML only; for the reverse use the JSON formatter tool or the CLI.
Strings that look like true/no/123/1.0 are quoted, otherwise a YAML parser would change their type.
Output targets the YAML 1.2 safe subset: not pretty, but parsed identically everywhere.