Case Study: One of the Largest U.S. Department Store Chains achieves a modern, high-performance Android e-commerce app with Grid Dynamics

Large-scale Android Application Modernization

One of the Largest Department Store engaged Grid Dynamics to modernize and standardize its legacy e-commerce Android application. The five‑year‑old app had grown into a tangled codebase with multiple implementations for the same features, mixed architectural patterns (MVC/MVP/MVVM), Java/Kotlin fragmentation, and a single‑activity structure, so the retailer required a full application rewrite and modernization rather than incremental refactoring.

Grid Dynamics delivered an Android application modernization—migrating the codebase to Kotlin and Clean/MVVM with Databinding, RxJava2, Dagger2 and Android Jetpack (NavGraph, ViewModel, LiveData, Room), modularizing the app (ADP/DA/DS/feature modules), introducing core ADP components and Firebase Remote Config kill switches, and removing legacy code. The overhaul produced measurable gains: App Store rating rose 4.0→4.8, crash rate fell from >1% to ~0.11%, Kotlin adoption reached 100%, repo size shrank, unit test coverage grew to >30%, CI/local build times dropped ~50% to <30m/<10m, 90% of APIs moved to protobuf with 2× faster responses, and a mobile web conversion uplift to 1.8%—all delivered by Grid Dynamics.