Ktor Tutorial

You have built a complete Ktor backend with authentication, database, WebSockets, Docker, and CI/CD. Now it is time to connect everything — a Kotlin backend and a Kotlin client sharing the same data models. In this final tutorial, you will create shared data models, build a Ktor Client that consumes your API, and see how a KMP mobile app connects to your backend. The Full-Stack Kotlin Vision Most full-stack projects look like this: ...

Your API has many endpoints. Other developers need to know how to use them. They need to know the request format, response format, required headers, and possible error codes. Writing documentation by hand is tedious and quickly becomes outdated. In this tutorial, you will add OpenAPI documentation and Swagger UI to your Ktor API. Developers can browse your API at /docs and try out endpoints directly from the browser. What is OpenAPI? OpenAPI (formerly Swagger) is a standard format for describing REST APIs. It is a YAML or JSON file that lists all endpoints, request bodies, response schemas, authentication, and more. ...

Your API has registration and login with email and password. But many users prefer to sign in with their Google account. It is faster and they do not need to remember another password. In this tutorial, you will add Google Sign-In using OAuth 2.0. You will learn how the OAuth flow works, how to handle the callback, and how to link OAuth accounts with existing email accounts. How OAuth 2.0 Works OAuth 2.0 is a protocol that lets users sign in with a third-party provider (Google, GitHub, etc.) without sharing their password with your application. ...

You decided to build a backend with Kotlin. Good choice. But now you face another decision: Ktor or Spring Boot? Both are great frameworks. Both support Kotlin. But they are very different in philosophy, design, and use cases. Let’s compare them honestly. The Big Picture Ktor is a lightweight, modular framework built by JetBrains. It is Kotlin-native, coroutine-based, and you add features as plugins. Spring Boot is a full-featured, batteries-included framework from VMware (now Broadcom). It started as a Java framework and added Kotlin support later. ...