Neil, You can send json data directly to a databin. Here is an example:

In[1]:= bin = CreateDatabin[]

Out[1]= Databin["....."]

In[2]:= json = 
 ExportString[{"x" -> 11, "y" -> "foo", "z" -> True}, "JSON"]

Out[2]= "{
    \"x\": 11,
    \"y\": \"foo\",
    \"z\": true
}"

In[3]:= URLFetch[
 "https://datadrop.wolframcloud.com/api/v1.0/Add?Bin=" <> bin["UUID"],
  "Body" -> json, "Headers" -> {"Content-Type" -> "application/json"},
  "Method" -> "POST"]

Out[3]= "<|\"Message\" -> \"The data was successfully added.\", \"Bin\
\" -> \"DD56f1e2eac88-e905-4ee5-8b18-7c4bd6072f3c\", \"Data\" -> \
<|\"x\" -> 11, \"y\" -> \"foo\", \"z\" -> True|>, \"Timestamp\" -> \
{2015, 7, 27, 13, 34, 52.135154`8.46970563570117}, \"DataID\" -> \
\"data0bcbcb32-146b-44f5-bcc2-caf713ac9b7d\", \"Information\" -> \
{\"EntryCount\" -> 1, \"LatestTimestamp\" -> 3646992892, \"Size\" -> \
512}|>"

In[4]:= Values[bin]

A couple of things to keep in mind:

• Make sure the "Content-Type" header in your request is set to "application/json"
• Data Drop will use the first level of parameters in the json submission. It will not separate nested

You can store your data as json in the databin and import it after reading it from the databin.

In[22]:= bin = CreateDatabin[];

In[23]:= DatabinAdd[
  bin, <|"myjson" -> 
    ExportString[<|"a" -> <|"a1" -> 1, "a2" -> RandomInteger[100]|>|>,
      "RawJSON"]|>];
DatabinAdd[
  bin, <|"myjson" -> 
    ExportString[<|"a" -> <|"a1" -> 2, "a2" -> RandomInteger[100]|>|>,
      "RawJSON"]|>];

In[25]:= data = Values[bin]

Out[25]= <|"myjson" -> {"{
    \"a\":{
        \"a1\":1,
        \"a2\":100
    }
   }", "{
    \"a\":{
        \"a1\":2,
        \"a2\":60
    }
   }"}|>

In[26]:= ImportString[#, "RawJSON"] & /@ data["myjson"]

Out[26]= {<|"a" -> <|"a1" -> 1, "a2" -> 100|>|>, <|"a" -> <|"a1" -> 2,
     "a2" -> 60|>|>}