Building Facebook Messenger

What this post added

This post details the technical challenges and solutions involved in building Facebook Messenger as a standalone app. Key technical contributions include overcoming long latency issues by building a new mechanism that maintains a persistent connection using the MQTT protocol for efficient mobile messaging, achieving phone-to-phone delivery in hundreds of milliseconds. It also discusses product decisions around seamlessly integrating different communication channels (chat, text, email) and the iterative testing process with colleagues to refine the user experience.