Jacob Kastrenakes, writing for The Verge:
Snapchat created Snapcash in partnership with Square, which will handle storing card numbers and processing payments. That's good news for a lot of reasons, including how user-friendly Square tends to be and the fact that it means Snapchat won't be handling your sensitive information. Snapchat has by no means proven itself to be a beacon of security, and having Square on board may make people a lot more comfortable about providing their information. Square has even been operating a very similar service of its own already, which works over email.