Must res.end() be called in express with node.js?

The answer to your question is no. You don’t have to call res.end() if you call res.send(). res.send() calls res.end() for you.

Taken from /lib/response.js, here is the end of the res.send() function:

  //. . .
  // respond
  this.end(head ? null : body);
  return this;
}