Chat App

1. The Question

“Design a mobile chat app with one-to-one conversations, small groups, attachments, and offline sending.”

Start with recoverable messaging. Presence and typing indicators should not be dependencies of sending a durable message. End-to-end encryption needs an explicit requirement because it changes keys, storage, and server content access.

Try your own design for ten minutes before reading the walkthrough.

2. The Walkthrough

Use the Five Step Method