Recently my Z10 got bricked. The only backup available was from April 2014. I bought a new Z10 and restored the backup on that phone. I was expecting that all WhatsApp messages and pictures received between April 2014 and the restoration date would not be available. But, WhatsApp did somehow pull the messages and pictures from recent months. So, where did it restore the messages/pictures from? From other contacts' phones?
WhatsApp definitely stores your messages on their server. They have to. If you send a WhatsApp message to someone and their phone is off, does it bounce? If not, they are storing your messages at some point.
Just because they say they don't store them forever really doesn't mean much, and I am pretty surprised by how many people on HN keep repeating it.
Recently my Z10 got bricked. The only backup available was from April 2014. I bought a new Z10 and restored the backup on that phone. I was expecting that all WhatsApp messages and pictures received between April 2014 and the restoration date would not be available. But, WhatsApp did somehow pull the messages and pictures from recent months. So, where did it restore the messages/pictures from? From other contacts' phones?