Building a Shared Networking Layer using ktor in KMP

Maintaining separate networking layers for Android and iOS often leads to code duplication and synchronisation headaches. By using Ktor, we can build a single, shared codebase for both the frontend networking and the backend API models. In this article, I’ll share how I built a shared networking layer for FieldSync, a project that handles authentication through a single reusable codebase. The Architecture: One Language, Two Ends In this project, I implemented an authentication flow (Phone Login & OTP) where the Data Transfer Objects (DTOs) are shared between the Ktor Server and the KMP Mobile app. Project Overview The project consists of modules: • shared: Contains the Ktor HTTP Client and Request/Response models. • server: A Ktor-based backend handling OTP generation. • Android/iOS Apps: Consuming the shared repository. Dependency Setup First, we ensure our libs.versions.toml and build.gradle.kts are synced. Both the server and the shared module need kotlinx-serialization. commonMain.