If this is your actual JSON:

'total'=>
    [
    'id' => 1,
    'name' => 1,
    'icon_id' => 503,
    ],
    'child'=>
    [
    'id' => 1,
    'group' => 0,
    'total_id' => 20,
  ...]

then it's malformed. You should check out the JSON spec . The long and the short of it is, JSON objects start and end with curly braces {} , keys are double-quoted "" and the separator between key and value is a colon : .

{
    "total" : {
      "id" : 1,
      "name" : 1,
      "icon_id" : 503
    },
    "child" :
    {
      "id" : 1,
      "group" : 0,
      "total_id" : 20
    } ...
  }

If you're trying to write ejson, that can be expressed as a map:

#{
  <<"total">> => #{
    <<"id">> => 1,
    <<"name">> => 1,
    <<"icon_id">> => 503
  },
  <<"child">> => #{
    <<"id">> => 1,
    <<"group">> => 0,
    <<"total_id">> => 20
   }..
}

or a tuple/list thing in erlang terms. There's a really helpful representation in the jiffy README that I've copied here:

Erlang                          JSON            Erlang
==========================================================================
null                       -> null           -> null
true                       -> true           -> true
false                      -> false          -> false
"hi"                       -> [104, 105]     -> [104, 105]
<<"hi">>                   -> "hi"           -> <<"hi">>
hi                         -> "hi"           -> <<"hi">>
1                          -> 1              -> 1
1.25                       -> 1.25           -> 1.25
[]                         -> []             -> []
[true, 1.0]                -> [true, 1.0]    -> [true, 1.0]
{[]}                       -> {}             -> {[]}
{[{foo, bar}]}             -> {"foo": "bar"} -> {[{<<"foo">>, <<"bar">>}]}
{[{<<"foo">>, <<"bar">>}]} -> {"foo": "bar"} -> {[{<<"foo">>, <<"bar">>}]}
#{<<"foo">> => <<"bar">>}  -> {"foo": "bar"} -> #{<<"foo">> => <<"bar">>}

It looks like your parser is expecting parsing out the ejson into an set of erlang terms like this:

{[{<<"foo">>, <<"bar">>}]} -> {"foo": "bar"} -> {[{<<"foo">>, <<"bar">>}]}

If your decoder has any ability to return a map, I would suggest you send that option along as they are MUCH MUCH easier to work with. If your decoder can't do that, then I would suggest you try and switch to using jiffy .