The Pragmatic Engineer

Building Reddit’s iOS and Android app

128 snips
Apr 23, 2025
Join Lauren Darcey, Head of Mobile Platform at Reddit, along with iOS Platform Lead Brandon Kobilansky and Principal Android Engineer Eric Kuck, as they dive into the nitty-gritty of building Reddit’s mobile apps. They discuss the complexities of a 2.5 million line codebase, the architectural shift to MVVM, and the strategic decisions behind using Jetpack Compose and avoiding SwiftUI. The trio also shares insights on improving developer experience, enhancing testing infrastructure, and the challenges of scaling a remote-first engineering team.
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ANECDOTE

Reddit's Massive Android Codebase

  • Reddit's Android app codebase has about 2.5 million lines of code and around 580 screens.
  • This scale surprises many, reflecting the app's surprising complexity beyond just feed and post screens.
ANECDOTE

Long Build Times Challenge

  • Reddit iOS full builds can take about 30 minutes, which is painfully long for developers.
  • Incremental builds are faster, and they encourage focused targets or playground modes to speed up development cycles.
ANECDOTE

Structure of Reddit Mobile Teams

  • Reddit's mobile platform teams each have about 10-11 engineers dedicated solely to iOS or Android.
  • They support roughly 200 mobile engineers assembled into about 20 feature teams across the company.
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