curl --request POST \
  --url https://int-api.mx.com/users/{user_guid}/spending_plans/{spending_plan_guid}/iterations/current/iteration_items \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "planned_amount": 110,
  "category_guid": "CAT-40faf068-abb4-405c-8f6a-e883ed541fff",
  "item_type": 1,
  "scheduled_payment_guid": "SCP-c731988a-712f-4f83-9b3b-0aa5b3d5208b",
  "top_level_category_guid": "CAT-9588eaad-90a4-bb5c-66c8-1812503d0db8"
}
'

import requests

url = "https://int-api.mx.com/users/{user_guid}/spending_plans/{spending_plan_guid}/iterations/current/iteration_items"

payload = {
    "planned_amount": 110,
    "category_guid": "CAT-40faf068-abb4-405c-8f6a-e883ed541fff",
    "item_type": 1,
    "scheduled_payment_guid": "SCP-c731988a-712f-4f83-9b3b-0aa5b3d5208b",
    "top_level_category_guid": "CAT-9588eaad-90a4-bb5c-66c8-1812503d0db8"
}
headers = {
    "Authorization": "Basic <encoded-value>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Basic <encoded-value>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    planned_amount: 110,
    category_guid: 'CAT-40faf068-abb4-405c-8f6a-e883ed541fff',
    item_type: 1,
    scheduled_payment_guid: 'SCP-c731988a-712f-4f83-9b3b-0aa5b3d5208b',
    top_level_category_guid: 'CAT-9588eaad-90a4-bb5c-66c8-1812503d0db8'
  })
};

fetch('https://int-api.mx.com/users/{user_guid}/spending_plans/{spending_plan_guid}/iterations/current/iteration_items', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://int-api.mx.com/users/{user_guid}/spending_plans/{spending_plan_guid}/iterations/current/iteration_items",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'planned_amount' => 110,
    'category_guid' => 'CAT-40faf068-abb4-405c-8f6a-e883ed541fff',
    'item_type' => 1,
    'scheduled_payment_guid' => 'SCP-c731988a-712f-4f83-9b3b-0aa5b3d5208b',
    'top_level_category_guid' => 'CAT-9588eaad-90a4-bb5c-66c8-1812503d0db8'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Basic <encoded-value>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://int-api.mx.com/users/{user_guid}/spending_plans/{spending_plan_guid}/iterations/current/iteration_items"

	payload := strings.NewReader("{\n  \"planned_amount\": 110,\n  \"category_guid\": \"CAT-40faf068-abb4-405c-8f6a-e883ed541fff\",\n  \"item_type\": 1,\n  \"scheduled_payment_guid\": \"SCP-c731988a-712f-4f83-9b3b-0aa5b3d5208b\",\n  \"top_level_category_guid\": \"CAT-9588eaad-90a4-bb5c-66c8-1812503d0db8\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Basic <encoded-value>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://int-api.mx.com/users/{user_guid}/spending_plans/{spending_plan_guid}/iterations/current/iteration_items")
  .header("Authorization", "Basic <encoded-value>")
  .header("Content-Type", "application/json")
  .body("{\n  \"planned_amount\": 110,\n  \"category_guid\": \"CAT-40faf068-abb4-405c-8f6a-e883ed541fff\",\n  \"item_type\": 1,\n  \"scheduled_payment_guid\": \"SCP-c731988a-712f-4f83-9b3b-0aa5b3d5208b\",\n  \"top_level_category_guid\": \"CAT-9588eaad-90a4-bb5c-66c8-1812503d0db8\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://int-api.mx.com/users/{user_guid}/spending_plans/{spending_plan_guid}/iterations/current/iteration_items")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Basic <encoded-value>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"planned_amount\": 110,\n  \"category_guid\": \"CAT-40faf068-abb4-405c-8f6a-e883ed541fff\",\n  \"item_type\": 1,\n  \"scheduled_payment_guid\": \"SCP-c731988a-712f-4f83-9b3b-0aa5b3d5208b\",\n  \"top_level_category_guid\": \"CAT-9588eaad-90a4-bb5c-66c8-1812503d0db8\"\n}"

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

{
  "actual_amount": 345,
  "category_guid": "CAT-40faf068-abb4-405c-8f6a-e883ed541fff",
  "created_at": "2016-10-13T18:08:00+00:00",
  "guid": "SPL-e5f9a5bd-c5b3-4901-bdc0-62119b9db262",
  "item_type": "1",
  "planned_amount": 110,
  "scheduled_payment_guid": "SCP-c731988a-712f-4f83-9b3b-0aa5b3d5208b",
  "spending_plan_iteration_guid": "SPI-848e6648-3fa3-4632-ac8f-e65f03167102",
  "top_level_category_guid": "CAT-9588eaad-90a4-bb5c-66c8-1812503d0db8",
  "transaction_guids": [
    "TRN-265abee9-889b-af6a-c69b-25157db2bdd9"
  ],
  "updated_at": "2016-10-13T18:09:00+00:00",
  "user_guid": "USR-fa7537f3-48aa-a683-a02a-b18940482f54"
}