Facebook Messenger Engineering with Mohsen Agsen

Facebook Messenger is a chat application that millions of people use every day to talk to each other. Over time, Messenger has grown to include group chats, video chats, animations, facial filters, stories, and many more features. Messenger is a tool for utility as well as for entertainment.

Messenger is used both on mobile and on desktop, but the size of the mobile application is particularly important on mobile. There are many users who are on devices that do not have much storage space.

As Messenger has accumulated features, the iOS code base has grown larger and larger. Several generations of Facebook engineers have rotated through the company with the responsibility of working on Facebook Messenger, which has led to different ways of managing information within the same codebase. The iOS codebase had room for improvement.

Project Lightspeed was a project within Facebook that had the goal of making Messenger on iOS much smaller. Mohsen Agsen is an engineer with Facebook, and he joins the show to talk about the process of rewriting the Messenger app.

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