So, let's calculate this: I pulled an image from a private facebook group, and the URL is of this form (although this particular URL is bogus, of course): ht

So, let's calculate this: I pulled an image from a private facebook group, and the URL is of this form (although this particular URL is bogus, of course): https://scontent-abc2-1.xx.fbcdn.net/v/t1.0-0/p600x600/35938454_4896129300617330_9044691654193995233_n.jpg?oh=cbfe497e1191ff4669103957691ba34b3&oe=92AC4028 We have a section of length 43 that can vary in the range [0-9] (that is, 10 possible values): 35938454_4896129300617330_9044691654193995233 A section of length 33 that appears to be in the range [0-9a-f] (that is, 16 possible values): cbfe497e1191ff4669103957691ba34b3 A section of length 8 in the range [0-9A-F] (that is, 16 possible values): 92AC4028 So how many different URLs are possible? 10 ^ 43 * 16 ^ 33 * 16 ^ 8 = ~ 10 ^ 92 ~ 2 ^ 306 This is a HUGE space, just to get a sense of it, adding 100 billion images a day, it would take ~ 10 ^ 80 YEARS for facebook to exhaust it! By the way, that's also how much it would take you to examine all of it while hunting for user's images (assuming this facebook endpoint does not even have rate limiting on it, which it almost certainly does).