I have installed Bump twice now, 1 year apart - on my iPhone, then on my Android. Both times it failed to bump files. I wonder if it has inherent issues.
That would account for "100 million downloads!" but not actual active users.
Just now it said "Network unavailable" while I was connected to WiFi. It found a network when I turned off WiFi, but still failed to Bump.
Bump needs to be something like Card.io. i.e. it needs to be a feature you license for inclusion in whatever app you're building. It never really made sense to me as a standalone app.