HTTP & APIs in Compose Desktop: Ktor Client & JSON Serialization | Kotlin Desktop #8

Build a Weather App with Compose Desktop! Learn Ktor Client with CIO engine, kotlinx.serialization for JSON parsing, suspend functions, loading states, and error handling — all in about 140 lines of Kotlin using the free Open-Meteo API (no API key needed). What You'll Learn: - Ktor Client with CIO engine for HTTP requests - ContentNegotiation plugin with JSON serialization - @Serializable data classes for API response mapping - @SerialName for mapping JSON field names to Kotlin properties - Suspend functions for asynchronous network calls - rememberCoroutineScope and scope.launch for UI coroutines - LaunchedEffect for initial data fetch on composition - Loading states with CircularProgressIndicator - Error handling with try-catch and user-friendly messages - when block for conditional UI rendering Timestamps: 0:00 - Introduction 0:15 - Preview: What We're Building 0:45 - Project Setup (Gradle, Ktor Dependencies) 2:36 - Weather Models (@Serializable Data Classes) 3:31 - Weather API (HttpClient, Fetch Function) 4:58 - App Content (State, Coroutines, UI) 8:14 - Main & Compile 9:56 - App Demo (Live Weather Data) 10:56 - Recap & Key Takeaways 11:56 - Thanks for Watching Key Takeaways: 1. HttpClient — Configure Ktor with CIO engine and JSON content negotiation 2. Suspend Functions — Network calls are suspend funs called from coroutine scopes 3. Data Classes — @Serializable and @SerialName for automatic JSON parsing 4. Loading States — when block handles loading, error, and success 5. Error Handling — try-catch with user-friendly error messages Previous Lesson: Lesson 07: Dialogs & Menus https://youtube.com/... Next Lesson: Lesson 09: Database & Storage (coming soon) Tech Stack: Kotlin 2.1, Compose Multiplatform 1.7.3, Material3 Ktor Client 3.0.3, kotlinx-serialization 1.7.3 Gradle 8.10, JVM 17+ API: Open-Meteo (free, no API key required) https://open-meteo.com Source Code: https://github.com/GoCelesteAI/kotlin_desktop_http_apis Taught by CelesteAI If you found this helpful, please like and subscribe for more Kotlin Desktop tutorials! #kotlin #compose #desktop #material3 #ktor #http #api #json #serialization #weather #tutorial #programming