http://www.erlang-projects.org/Public/news/ejson/view

There’s also the mochijson module in mochiweb but this looks useful in situations where the entirety of mochiweb might be overkill.

When ejabberd or Jabberlang return “error: -12″ this means they cannot load their native library drivers. Normally this means they can’t find expat_erl.so.

To fix:

1. Verify the drivers exist in the priv directory of the Jabberlang or ejabberd applications, depending on which one you’re using.
2. Verify the path, returned by ejabberd:get_so_path(), exists and is readable by the user the Erlang process is running under.
3. Make sure the shared library has been built for the appropriate platform. In other words, make sure you’re not loading a Linux shared library on OS X, for example.

May Google find this so someone else doesn’t experience the pain I did yesterday.