Jan Rabe
Tech Lead
I lead native app development at CHECK24 Profis in Berlin. 15 years of mobile development across Android and iOS, 30+ app projects, and enough opinions to fill a conference talk, although hopefully wise enough to know when to let them go. I build tools, lead teams, and raise a toddler who is teaching me more about graceful failure recovery than any production incident ever did.
Where Do the Bytes Go? Making iOS App Growth Observable at Scale
App size is one of the few product metrics that directly affects App Store conversion, yet most iOS teams can only see it as a single opaque number.
In this talk, I’ll show how we made app size understandable and actionable in a large-scale iOS codebase.
We built Caliper, an open-source Swift CLI tool that analyzes IPA files, LinkMap output, and asset catalogs to break app size down into modules, dependencies, and resources. It turns build artifacts into structured reports that make growth visible and attributable.
At CHECK24 Profis, this approach helped reduce our app size from 95 MB to 21.62 MB by exposing hidden contributors and making ownership of changes explicit across teams.
I’ll walk through how iOS app size is actually composed, how we extract meaningful signals from build outputs, and how we integrated this into CI to prevent regressions.