REM: REST API for Prototyping from Heroku

http://rem-rest-api.herokuapp.com/

REM is a REST API for prototyping. It accepts JSON requests, returns JSON responses and persists data between requests like a real API. But your test data is only visible to you. It's CORS enabled and no API key is required.

var xhr = new XMLHttpRequest()
xhr.open("GET", "http://rem-rest-api.herokuapp.com/api/users", true)
xhr.withCredentials = true
xhr.send()
xhr.onload = function() {
  var data = JSON.parse(xhr.responseText)
}