The Pragmatic Engineer·tech·7 min
Building WhatsApp with Jean Lee
Jean Lee, engineer number 19 at WhatsApp, shares her experience of building the messaging app with a tiny team of 30 engineers. The team kept things simple, saying no to most feature requests, and chose Erlang for the backend. They also avoided cross-platform abstractions and charged users $1 per year, which paid everyone's salaries and kept growth intentionally slow.
The team had close to zero formal processes, with no code reviews after the first commit, and no Scrum or Agile methodologies. Despite this, they were able to outcompete larger companies like Skype. Jean attributes this to the trust and ownership within the team, which allowed them to move faster and be more efficient.
WhatsApp's approach to feature development was also unique. They delayed video calling for years until it was extremely polished, and tested features extensively with family members before releasing them publicly. The company's CEO, Jan Koum, rejected 99% of feature requests, prioritizing reliability and simplicity.
The Facebook acquisition of WhatsApp in 2014 brought significant changes to the company. Jean shares her experience of transitioning from an individual contributor to a manager at Facebook, including the reality of calibration meetings and performance reviews. She also discusses how AI can enable smaller engineering teams, but believes that human touch is still essential in engineering management.
Jean's advice to new grads is to invest in the fundamentals, as tools and languages come and go, but foundations remain. She also emphasizes the importance of ownership and trust within a team, and how visible metrics can create accountability without bureaucracy. Overall, WhatsApp's experience suggests that simplicity, trust, and ownership can be more important than tools or formal processes in achieving success.