What is the most mature JSON library for Erlang?

I prefer Jiffy. It works with binary and is realy fast.

1> jiffy:decode(<<"{\"Name\":\"Tom\",\"Age\":10}">>).
{[{<<"Name">>,<<"Tom">>},{<<"Age">>,10}]}

Can encode as well:

2> jiffy:encode({[{<<"Name">>,<<"Tom">>},{<<"Age">>,10}]}).
<<"{\"Name\":\"Tom\",\"Age\":10}">>

I use the json library provided by yaws.

Edit: I actually switched over to Jiffy, see Konstantin's answer.

Also check out jsx. "An erlang application for consuming, producing and manipulating json. Inspired by Yajl." I haven't tried it myself yet, but it looks promising.

As a side note; I found this library through Jesse, a json schema validator by Klarna.

Have a look at the one from mochiweb: mochijson.erl

1> mochijson:decode("{\"Name\":\"Tom\",\"Age\":10}").   
{struct,[{"Name","Tom"},{"Age",10}]}