Loobback 3 custom routes

loopback-custom-routes.js

module.exports = function (app) {
  // Install a "/ping" route that returns "pong"
  app.get('/ping', function (req, res) {
    res.send('pong');
  });

  //  Express router middleware
  var router = app.loopback.Router();
  router.get('/ping_express', function (req, res) {
    res.send('pongaroo');
  });

  app.use(router);
}

you can place this file in your loopback 3 boot folder to run this route