Ask HN: Internet controlled padlock.

Does anybody know of a padlock that can be controlled remotely via the internet? I'm not talking about the front door to my house, but a padlock (the type you would use to lock a chain around a gate). I have had a look around but can't seem to find anything. I am looking for a padlock with a keypad that you can assign different codes to different people for. Ideally there would be something like lockitron (https://lockitron.com/) but for a padlock. If you know of a padlock that can open via a swipe card, that could work also. If anybody knows anything out there, I would love to hear about it. Thanks! Clark