This is jo, a small utility to create JSON objects. Jo tries to be clever about types and knows null, booleans, strings and numbers. It does arrays, and it pretty-prints on demand. If a key’s value begins with an opening brace ({) or a bracket ([]) we attempt to decode JSON from it; this allows jo to add objects or arrays (use -a!) to itself. jo also supports nested types natively.
In the AUR as jo-git.