This paper presents research on the use of Kotlin Multiplatform technology for developing mobile applications targeting both Android and iOS platforms. The study includes performance measurements, architectural analysis, and comparative evaluation with native approaches to assess the cost-effectiveness and sustainability of this solution. Three functionally identical applications were developed: one using Kotlin Multiplatform, one natively for Android, and one natively for iOS. The findings show that while Kotlin Multiplatform may have slight drawbacks in areas such as memory usage, it offers significant benefits in development speed, maintainability, and code reusability, making it a compelling choice for projects with substantial cross-platform logic sharing.