Shorten ObjectId in node.js and mongoose

my URLs look like this at the moment:

http://ift.tt/1EQjk5u.....

So, as you can see, it gets pretty long, pretty fast. I was thinking about shortening these ObjectIds. Idea is that I should add new field called "shortId" to every model in my database. So instead of having:

var CompanySchema = mongoose.Schema({
  /* _id will be added automatically by mongoose */
  String name;
  String address;
  String directorName;
});

we would have this:

var CompanySchema = mongoose.Schema({
  /* _id will be added automatically by mongoose */
  String shortId; /* WE SHOULD ADD THIS */
  String name;
  String address;
  String directorName;
});

I found a way to do it like this:

// Encode
var b64 = new Buffer('47cc67093475061e3d95369d', 'hex')
  .toString('base64')
  .replace('+','-')
  .replace('/','_')
;
// -> shortID is now: R8xnCTR1Bh49lTad

But I still think it could be shorter.

Also, I found this npm module: http://ift.tt/1ajrpXc but I don't see it's being used too much so I can't tell if it's reliable.

Anyone has any suggestions?