curl --request POST \
  --url https://auth.routee.net/oauth/token \
  --header 'authorization: Basic NTc1NmE0MTFlNGIwNmEzM2Q1MDUxN2M3OnZiNlFwakNJT0c=' \
  --header 'content-type: application/x-www-form-urlencoded' \
  --data grant_type=client_credentials

OkHttpClient client = new OkHttpClient();

MediaType mediaType = MediaType.parse("application/x-www-form-urlencoded");
RequestBody body = RequestBody.create(mediaType, "grant_type=client_credentials");
Request request = new Request.Builder()
  .url("https://auth.routee.net/oauth/token")
  .post(body)
  .addHeader("authorization", "Basic NTc1NmE0MTFlNGIwNmEzM2Q1MDUxN2M3OnZiNlFwakNJT0c=")
  .addHeader("content-type", "application/x-www-form-urlencoded")
  .build();

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

var client = new RestClient("https://auth.routee.net/oauth/token");
var request = new RestRequest(Method.POST);
request.AddHeader("content-type", "application/x-www-form-urlencoded");
request.AddHeader("authorization", "Basic NTc1NmE0MTFlNGIwNmEzM2Q1MDUxN2M3OnZiNlFwakNJT0c=");
request.AddParameter("application/x-www-form-urlencoded", "grant_type=client_credentials", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

<?php

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => "https://auth.routee.net/oauth/token",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => "grant_type=client_credentials",
  CURLOPT_HTTPHEADER => array(
    "authorization: Basic NTc1NmE0MTFlNGIwNmEzM2Q1MDUxN2M3OnZiNlFwakNJT0c=",
    "content-type: application/x-www-form-urlencoded"
  ),
));

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

curl_close($curl);

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

import http.client

conn = http.client.HTTPSConnection("auth.routee.net")

payload = "grant_type=client_credentials"

headers = {
    'authorization': "Basic NTc1NmE0MTFlNGIwNmEzM2Q1MDUxN2M3OnZiNlFwakNJT0c=",
    'content-type': "application/x-www-form-urlencoded"
    }

conn.request("POST", "/oauth/token", payload, headers)

res = conn.getresponse()
data = res.read()

print(data.decode("utf-8"))

require 'uri'
require 'net/http'

url = URI("https://auth.routee.net/oauth/token")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE

request = Net::HTTP::Post.new(url)
request["authorization"] = 'Basic NTc1NmE0MTFlNGIwNmEzM2Q1MDUxN2M3OnZiNlFwakNJT0c='
request["content-type"] = 'application/x-www-form-urlencoded'
request.body = "grant_type=client_credentials"

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

var settings = {
  "async": true,
  "crossDomain": true,
  "url": "https://auth.routee.net/oauth/token",
  "method": "POST",
  "headers": {
    "authorization": "Basic NTc1NmE0MTFlNGIwNmEzM2Q1MDUxN2M3OnZiNlFwakNJT0c=",
    "content-type": "application/x-www-form-urlencoded"
  },
  "data": {
    "grant_type": "client_credentials"
  }
}

$.ajax(settings).done(function (response) {
  console.log(response);
});

#import <Foundation/Foundation.h>

NSDictionary *headers = @{ @"authorization": @"Basic NTc1NmE0MTFlNGIwNmEzM2Q1MDUxN2M3OnZiNlFwakNJT0c=",
                           @"content-type": @"application/x-www-form-urlencoded" };

NSMutableData *postData = [[NSMutableData alloc] initWithData:[@"grant_type=client_credentials" dataUsingEncoding:NSUTF8StringEncoding]];

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"https://auth.routee.net/oauth/token"]
                                                       cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                   timeoutInterval:10.0];
[request setHTTPMethod:@"POST"];
[request setAllHTTPHeaderFields:headers];
[request setHTTPBody:postData];

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request
                                            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                if (error) {
                                                    NSLog(@"%@", error);
                                                } else {
                                                    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
                                                    NSLog(@"%@", httpResponse);
                                                }
                                            }];
[dataTask resume];

{
   "access_token":"string",
   "token_type":"string",
   "expires_in":"number",
   "scope":"string,string,string",
   "permissions":[
      "string"
   ]
}