List customers

curl --request GET \
  --url https://api.staging.streamlinedpayments.com/api/v1/customers \
  --header 'X-Api-Key: <api-key>' \
  --header 'X-App-Id: <api-key>'

const options = {method: 'GET', headers: {'X-App-Id': '<api-key>', 'X-Api-Key': '<api-key>'}};

fetch('https://api.staging.streamlinedpayments.com/api/v1/customers', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.staging.streamlinedpayments.com/api/v1/customers"

headers = {
    "X-App-Id": "<api-key>",
    "X-Api-Key": "<api-key>"
}

response = requests.get(url, headers=headers)

print(response.text)

require 'uri'
require 'net/http'

url = URI("https://api.staging.streamlinedpayments.com/api/v1/customers")

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

request = Net::HTTP::Get.new(url)
request["X-App-Id"] = '<api-key>'
request["X-Api-Key"] = '<api-key>'

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