Engineering. When to Use KSP for Code Generation in Android Apps

Kotlin Symbol Processing (KSP) has emerged as the modern standard for code generation in Android development, replacing older annotation processing methods. When you annotate a data class with @JsonClass(generateAdapter = true), KSP automatically generates the corresponding JsonAdapter during the build process, placing it in build/generated/ksp without requiring manual implementation. This approach has become the default choice for Android libraries that need to transform annotations into generated code, making it a natural first option when developers require custom code generation capabilities.

RevenueCat's Codegen Gradle Plugin exemplifies this pattern by leveraging KSP to generate type-safe Kotlin accessors for managing entitlements (features unlocked by purchases) and offerings (products available for sale). For mobile app studios focused on monetization, understanding when and how to implement KSP-based code generation can streamline the integration of in-app purchase systems and reduce runtime errors through compile-time type safety. The decision to use KSP should consider your project's complexity, the volume of generated code, and whether the build-time overhead justifies the developer experience gains and type safety benefits it provides.