express seems rather tiny to me, compared with other packages.

One use case where even this package seems not justified is if I have to start up an http server only for one interaction, such as authenticating a desktop app with OAuth 2.0 with localhost as the loopback URI.

The following code snippet illustrates this, and also shows that code = req.query.code (which would be possible with express) must be replaced with something lengthier:

var oAuth2Client = new google.auth.OAuth2(...);
var loopback = http.createServer(function(req, res) {
  var code = new URL("http://" + req.url).searchParams.get("code");
  if (code) {
    oAuth2Client.getToken(code, (err, token) => {
      oAuth2Client.setCredentials(token);
      res.end();
    });
    loopback.close();
  }
}).listen(...);