var request = require("request");
var accountSid = "XXXXXXXXX";
var accountToken = "YYYYYYYYY";
var authKey = "ZZZZZZZZZZ";

var encoding = Buffer.from(authKey + ':' + accountToken).toString('base64')

var options = {
  'method': 'GET',
  'url': 'https://leadassist.exotel.in/v1/tenants/'+accountSid+'/greenvn?page_size=2&cursor=1&time_to=2021-02-01T00:00:00&time_from=2021-01-01T00:00:00&status=active',
  'headers': {
    'Authorization': 'Basic ' + encoding
  }
};
request(options, function (error, response) {
  if (error) throw new Error(error);
  console.log(response.body);
});

<?php
$curl = curl_init();
$accountSid = "XXXXXXXXXX";
$accountToken = "YYYYYYYYYY";
$authKey = "ZZZZZZZZZZ";

$encoding = base64_encode($authKey .":". $accountToken);
curl_setopt_array($curl, array(
  CURLOPT_URL => 'https://leadassist.exotel.in/v1/tenants/'+$accountSid+'/greenvn?page_size=2&cursor=1&time_to=2021-02-01T00:00:00&time_from=2021-01-01T00:00:00&status=active',
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 0,
  CURLOPT_FOLLOWLOCATION => true,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => 'GET',
  CURLOPT_HTTPHEADER => array(
    'Authorization: Basic '+ $encoding
  ),
));

$response = curl_exec($curl);

curl_close($curl);
echo $response;

import requests, base64, json

accountSid = "XXXXXXXXX"
authToken = "YYYYYYYYY"
authKey = "ZZZZZZZZZZ"

encoding = base64.b64encode(authKey + ":" + authToken)
url = "https://leadassist.exotel.in/v1/tenants/"+ accountSid+"/greenvn?page_size=2&cursor=1&time_to=2021-02-01T00:00:00&time_from=2021-01-01T00:00:00&status=active"

payload={}
headers = {
  'Authorization': 'Basic '+encoding
}

response = requests.request("GET", url, headers=headers, data=payload)

print(response.text)

package main

import (
	b64 "encoding/base64"
	"fmt"
	"io/ioutil"
	"net/http"
)

func main() {
	// Please provide accountSid, authToken from your Exotel account
	accountSid := "XXXXXXXXX"
	authToken := "YYYYYYYY"
	authKey := "ZZZZZZZZZZ"

	// Encoding the accountSid and authToken, used in Authorization header
	encoding := b64.StdEncoding.EncodeToString([]byte(authKey + ":" + authToken))
	url := "https://leadassist.exotel.in/v1/tenants/" + accountSid + "/greenvn?page_size=2&cursor=1&time_to=2021-02-01T00:00:00&time_from=2021-01-01T00:00:00&status=active"
	method := "GET"

	client := &http.Client{}
	req, err := http.NewRequest(method, url, nil)

	if err != nil {
		fmt.Println(err)
		return
	}
	req.Header.Add("Authorization", "Basic "+encoding)
	res, err := client.Do(req)
	if err != nil {
		fmt.Println(err)
		return
	}
	defer res.Body.Close()

	body, err := ioutil.ReadAll(res.Body)
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Println(string(body))
}