require "uri"
    require "net/http"

    url = URI("https://app.sell.do//api/leads/create.json")

    http = Net::HTTP.new(url.host, url.port)

    request = Net::HTTP::Post.new(url)
    request["Content-Type"] = "application/json"
    request.body = "{\n  \"form_id\": \"123456789012345678901234\",\n  \"sell_do\" : {\n    \"campaign\" : {\n      \"srd\" : \"\",\n      \"campaign_id\": \"\"\n    },\n    \"form\": {\n      \"lead\": {\n        \"name\": \"amurat11abprimetest\",\n        \"email\": \"qwt@qw.rty\",\n        \"phone\": \"+911234567890\",\n        \"project_id\": \"\",\n        \"campaign_id\": \"\",\n        \"sales\":\"\",\n        \"profile\": {\n          \"company\": \"amura\"\n        }\n      },\n      \"custom\" : {\n        \"c_one\" : \"c one\"\n      },\n      \"note\" : {\n        \"content\" : \"note content\"\n      },\n      \"requirement\" : {\n        \"bhk\": [2, 3],\n        \"property_type\" : \"flat\",\n        \"purpose\" : \"end_use\",\n        \"locations\" : \"pune\",\n        \"min_budget\" : \"100000\",\n        \"max_budget\" : \"200000\",\n        \"min_possession\" : \"12\",\n        \"max_possession\" : \"24\"\n      }\n    }\n  },\n  \"api_key\" : \"123456789012345678901234dasdasda\"\n}\n"

    response = http.request(request)
    puts response.read_body
  

    OkHttpClient client = new OkHttpClient();

    MediaType mediaType = MediaType.parse("application/json");
    RequestBody body = RequestBody.create(mediaType, "{\n  \"form_id\": \"123456789012345678901234\",\n  \"sell_do\" : {\n    \"campaign\" : {\n      \"srd\" : \"\",\n      \"campaign_id\": \"\"\n    },\n    \"form\": {\n      \"lead\": {\n        \"name\": \"asd asd\",\n        \"email\": \"qwt@qw.rty\",\n        \"phone\": \"911234567890\",\n        \"project_id\": \"\",\n        \"campaign_id\": \"\",\n        \"sales\":\"\",\n        \"profile\": {\n          \"company\": \"amura\"\n        }\n      },\n      \"custom\" : {\n        \"c_one\" : \"c one\"\n      },\n      \"note\" : {\n        \"content\" : \"note content\"\n      },\n      \"requirement\" : {\n        \"bhk\": [2, 3],\n        \"property_type\" : \"flat\",\n        \"purpose\" : \"end_use\",\n        \"locations\" : \"pune\",\n        \"min_budget\" : \"100000\",\n        \"max_budget\" : \"200000\",\n        \"min_possession\" : \"12\",\n        \"max_possession\" : \"24\"\n      }\n    }\n  },\n  \"api_key\" : \"6a6854e70e4be582de82bf5c4861ab11\"\n}\n");

    Request request = new Request.Builder()
    .url("https://app.sell.do//api/leads/create.json")
    .post(body)
    .addHeader("Content-Type", "application/json")
    .addHeader("cache-control", "no-cache")
    .build();

    Response response = client.newCall(request).execute();
  

PHP : 

    <?php

    $request = new HttpRequest();
    $request->setUrl("https://app.sell.do//api/leads/create.json");
    $request->setMethod(HTTP_METH_POST);

    $request->setHeaders(array(
    'cache-control' => 'no-cache',
    'Content-Type' => 'application/json'
    ));

    $request->setBody('{
      "form_id": "123456789012345678901234",
      "sell_do" : {
        "campaign" : {
          "srd" : "123456789012345678901234",
          "campaign_id": ""
        },
        "form": {
          "lead": {
            "name": "asd asd",
            "email": "qwt@qw.rty",
            "phone": "+911234567890",
            "project_id": "",
            "campaign_id": "",
            "sales":"",
            "profile": {
              "company": "amura"
            }
          },
          "custom" : {
            "c_one" : "c one"
          },
          "note" : {
            "content" : "note content"
          },
          "requirement" : {
            "bhk": [2, 3],
            "property_type" : "flat",
            "purpose" : "end_use",
            "locations" : "pune",
            "min_budget" : "100000",
            "max_budget" : "200000",
            "min_possession" : "12",
            "max_possession" : "24"
          }
        }
      },
      "api_key" : "123456789012345678901234dasdasda"
    }
    ');

    try {
    $response = $request->send();
    echo $response->getBody();
    } catch (HttpException $ex) {
    echo $ex;
    }