Api

In the previous tutorial, you learned Server Components. Now let’s add a backend — Route Handlers for APIs and Server Actions for mutations. Two Ways to Write Server Code Next.js gives you two tools for server-side logic: Route Handlers — traditional REST API endpoints (app/api/route.ts) Server Actions — functions that run on the server, called from the client Use Route Handlers when you need a public API (for mobile apps, third-party clients, or webhooks). Use Server Actions for form submissions and mutations within your Next.js app. ...

In the Compose series, you learned basic Retrofit: define an interface, call an endpoint, show the result. That works for tutorials. In production, you need more. Authentication tokens that refresh automatically. Logging for debugging. Retry logic for flaky networks. Proper error handling that shows meaningful messages. This tutorial builds a production-ready API layer with Retrofit 3, Kotlin Serialization, and OkHttp interceptors. Prerequisites: Compose Tutorial #12: Retrofit basics and Kotlin Tutorial: Serialization. Why Kotlin Serialization Over Gson? Retrofit traditionally used Gson for JSON parsing. Kotlin Serialization is better for modern Android: ...

In the previous article, you built a CLI tool with AI. Now let us scale up. You are going to build a complete REST API — with a database, authentication, tests, and deployment — all driven by AI. The project: a Notes API that lets users create, read, update, and delete notes. It includes user registration, authentication with JWT, PostgreSQL storage, and proper error handling. Simple enough to build in one session, complex enough to show real patterns. ...

In the previous tutorial, we built a CLI tool with Click and Rich. Now let’s build a REST API — a web API that any frontend, mobile app, or other service can call. We will use FastAPI, the fastest-growing Python web framework. It has automatic documentation, type checking, and built-in validation. By the end of this tutorial, you will have a working Bookmark Manager API. Why FastAPI? Automatic API docs — Swagger UI at /docs (free, no setup) Type-safe — uses Python type hints for validation Fast — built on Starlette and Pydantic (one of the fastest Python frameworks) Async support — native async/await (from Tutorial #18) Pydantic validation — automatic input validation (from Tutorial #10) Install the dependencies: ...

In the previous tutorial, we learned about async/await and asyncio. Now let’s learn about HTTP requests and APIs — how to call REST APIs, send data, handle responses, and build a reusable API client. Almost every Python application talks to an API at some point. Weather data, payment processing, social media, databases — they all use HTTP. By the end of this tutorial, you will know how to make HTTP requests, handle errors, and build a clean API client. ...

Every app needs to talk to the internet. On Android, you use Retrofit. On iOS, you use URLSession. Two different libraries, two different APIs, two different codebases. In KMP, you use Ktor Client — one networking library that works on every platform. Write your API calls once in commonMain, and they work on Android, iOS, Desktop, and Web. What is Ktor? Ktor is a networking framework by JetBrains (the same team behind Kotlin). The client side lets you make HTTP requests from shared code. ...

Every real app needs data from the internet. A weather app calls a weather API. A social app loads posts from a server. A store app fetches products from a backend. Retrofit is the most popular library for making HTTP requests in Android. In this tutorial, you will learn how to use it with Compose to build a screen that loads, displays, and handles errors from a real API. What is Retrofit? Retrofit is an HTTP client library by Square. It turns your API into a Kotlin interface: ...

In the previous tutorial, you built a CLI tool. Now let’s build a REST API. Ktor is Kotlin’s official framework for building asynchronous servers and clients. It is lightweight, flexible, and uses Kotlin coroutines. In this tutorial, you will learn: Setting up Ktor Routing (GET, POST, PUT, DELETE) JSON serialization with Content Negotiation In-memory storage Path parameters and query parameters Error handling with StatusPages Testing with ktor-server-test-host What We’re Building A Notes API with CRUD operations: ...