curl --request POST \
  --url https://api.erlcrussia.com/v3/users \
  --header 'Content-Type: application/json' \
  --header 'erlcrussia-api-key: <api-key>' \
  --data '
{
  "discordIds": [
    "123456789012345678",
    "234567890123456789"
  ],
  "robloxIds": [
    "261"
  ]
}
'

import requests

url = "https://api.erlcrussia.com/v3/users"

payload = {
    "discordIds": ["123456789012345678", "234567890123456789"],
    "robloxIds": ["261"]
}
headers = {
    "erlcrussia-api-key": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {'erlcrussia-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({discordIds: ['123456789012345678', '234567890123456789'], robloxIds: ['261']})
};

fetch('https://api.erlcrussia.com/v3/users', 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://api.erlcrussia.com/v3/users",
  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([
    'discordIds' => [
        '123456789012345678',
        '234567890123456789'
    ],
    'robloxIds' => [
        '261'
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "erlcrussia-api-key: <api-key>"
  ],
]);

$response = curl_exec($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://api.erlcrussia.com/v3/users"

	payload := strings.NewReader("{\n  \"discordIds\": [\n    \"123456789012345678\",\n    \"234567890123456789\"\n  ],\n  \"robloxIds\": [\n    \"261\"\n  ]\n}")

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

	req.Header.Add("erlcrussia-api-key", "<api-key>")
	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://api.erlcrussia.com/v3/users")
  .header("erlcrussia-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"discordIds\": [\n    \"123456789012345678\",\n    \"234567890123456789\"\n  ],\n  \"robloxIds\": [\n    \"261\"\n  ]\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.erlcrussia.com/v3/users")

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

request = Net::HTTP::Post.new(url)
request["erlcrussia-api-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"discordIds\": [\n    \"123456789012345678\",\n    \"234567890123456789\"\n  ],\n  \"robloxIds\": [\n    \"261\"\n  ]\n}"

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

[
  {
    "discordId": "123456789012345678",
    "robloxId": "156"
  },
  {
    "discordId": "345678901234567890",
    "robloxId": "261"
  }
]