Just found 17TRACK has published sign up feature but not on their homepage yet. It's only available for app users.

As registered members, you can save your shipments, bulk tracking and get alerted/email notification when shipping status changes.

Here's the access to sign up:

user.17track.net

Keep in mind, select a proper role, as seller / buyer / carriers. And these roles are unique, you won't be able to change your role when registration is done.