1. You are keeping chats that are meant to be ephemeral 2. You are acting as a snapchat client to create an API where there should not be one. 3. You are basically spamming users on snapchat to get them to add you.
I think quite a few of those terms have been violated.
Good Job on the Tech!!
"How does it work?
We communicate with Snapchat's servers and pretend to be their mobile app. This gives us access to everything that you can do through the mobile app. For example, we can send messages, view (and save) messages, create new accounts..."
That's a detail that's not relevant at all to their "users" (the people sending in snapchats). It sounds like they're bragging about their circumvention of Snapchat's lack of an API.
I don't want to diminish the technical accomplishment here -- reverse an engineering an API and writing a Snapchat bot is impressive. But, as other posters have pointed out, they're likely violating the Snapchat terms and misleading their "users."
On another note, the only way an app dev could really prevent this is if mobile devices had some sort of TPM or other remote attestation feature.
We basically built something on top of Snapchat, which is a relatively-new social photo sharing app with no API for developers. So we made our own APIs and made Ranker.io work :)
A bot named 'epicchallenge' programmatically sends a snapchat video about a "smile" contest to a huge (42k) list of users. Then we programmatically get their responses and have people vote on them.