I'm here

I would be surprised if the following hasn't occurred to chat apps like WhatsApp that ends up with large groups. Here's the deal: when I visit a place I should be able to declare in a group that I'm around. If someone in the group is also within a (configurable) radius (say 5 km), they can get a notification. If they want to hit me up, they can ping. I wouldn't know who saw the notification, so no…