They released Memories last year which lets you back up your sent Snapchats with them. So I'd expect some non trivial permanent storage costs, at least at their scale.

https://www.snap.com/en-US/news/post/introducing-memories/

1. There are also stories (last 24 hours). These are often video clips.

2. Like Whatsapp, server has to store the message until the receiver is online again (until they open the app).

3. Whatever systems they use for advertising, tracking, profiling, and analytics is probably a significant chunk of their backend.

> 2. Like Whatsapp, server has to store the message until the receiver is online again (until they open the app).

The server actually has to store it for a maximum of 30 days [0]. Snaps get deleted after 30 days (even if they're unopened). They're deleted immediately once the Snapchat servers get confirmation they've been viewed.

[0]: https://www.snap.com/en-US/news/post/how-snaps-are-stored-an...

Do you really believe that.

Sure, why not? They might work with the FBI to store data for specific targets, and the NSA probably intercepts and copies a lot of data onto their own servers, but I see no reason why the company itself would lie about this. They probably do delete the data immediately for the vast majority of their users.

I imagine bandwidth is a major cost center.

Last time I checked, Google and AWS both had very, very high egress prices. At these levels, it's far cheaper to connect to a Tier 1 provider or three.

Did you check what their price was at the $2B purchase volume?

Nope. OTOH, $2B is large enough that the Tier 1 transit rates are probably quite good, too.

I suppose you're confusing the user-facing feature with what actually happens on their servers.