Despite being a voice and text chat app, Discord sees over a hundred million images passing through its tubes every day. While we wish it was as simple as sending them out across the tubes to your friends, delivering these images creates some pretty large technical problems. Linking directly to images would leak users’ IP addresses to image hosts, and large images use up lots of bandwidth. To circumvent these problems, Discord needs an intermediary service to fetch images on behalf of users and then resize them to reduce bandwidth usage.


https://blog.discordapp.com/how-discord-resizes-150-million-images-every-day-with-go-and-c-c9e98731c65d