Your single-module app compiles in 45 seconds. You add more features. More screens. More dependencies. Now it takes 3 minutes. Every small change triggers a full rebuild. Worse, any file can import any other file. Your UI layer imports database classes directly. A junior developer bypasses the repository and calls the DAO from a Composable. There are no boundaries. Multi-module architecture fixes both problems. Faster builds (Gradle only recompiles changed modules) and enforced boundaries (modules can only access what they depend on). ...

Your ViewModel starts simple. It loads data from a repository and shows it on screen. Then product requirements arrive: filter tasks by priority, sort by due date, combine tasks with user data, validate input before saving. The ViewModel grows. It becomes 500 lines of mixed UI logic and business rules. Testing one rule means setting up the entire ViewModel. Use cases fix this. Each use case is one business operation. One class. One job. Easy to test. Easy to reuse across ViewModels. ...

Your app calls an API. It also reads from a local database. Sometimes the API is down. Sometimes the user has no internet. Where does the data come from? Without a clear answer, your app becomes unpredictable. One screen shows fresh data from the API. Another screen shows stale data from the database. The user sees different information depending on which screen they check first. The repository pattern solves this. It gives your app a single source of truth — one place where data lives. Every screen reads from the same source. ...

In the previous tutorial, you learned about Clean Architecture layers. But there is a problem — who connects everything together? Who creates the repository and gives it to the ViewModel? Who creates the database and gives it to the repository? You could wire everything manually. But with 10 ViewModels, 5 repositories, and 3 data sources, you will spend more time wiring than coding. Hilt solves this. You annotate your classes and Hilt connects everything automatically. It is Google’s recommended DI framework for Android. ...

Your first Android app works fine with everything in one file. But as the app grows, things fall apart. You add more screens. More API calls. More database queries. Suddenly, one change breaks three unrelated features. This is the architecture problem. And it is the reason most real-world apps follow a structured pattern. In this tutorial, you will learn the three most important architecture patterns for Android: MVVM, MVI, and Clean Architecture. You will understand when to use each one and how they work together. ...

This is the capstone article. Everything from 14 projects comes together. We started this series with a CLI todo app that took 35 minutes. Then we built REST APIs, Chrome extensions, full-stack blogs, SaaS dashboards, and mobile apps. Each project taught us something about working with Claude Code. Now the question: can we take a real product idea — something that could make money — from concept to deployed, production-ready app in a single working day? ...

Mobile development is hard. Cross-platform mobile development is harder. Kotlin Multiplatform sits in the middle — shared business logic with native UI on each platform. The Gradle configuration alone can take hours. Can Claude handle it? This is the most technically challenging project in the entire series. KMP has expect/actual declarations, platform-specific dependency injection, multiplatform Gradle config, and two completely different UI frameworks (Jetpack Compose for Android, SwiftUI for iOS). ...

Every article so far has used one Claude Code session. One terminal, one conversation, one context. That works for small projects, but what about larger codebases where different parts can be built in parallel? Claude Code supports multiple agents working on the same project. You can have one agent building the backend, another building the frontend, and a third writing tests — all at the same time. This article tests whether multi-agent development actually works. Does it save time? What happens when agents step on each other’s code? How do you coordinate? ...

SaaS boilerplate kits sell for $200-$500 on marketplaces. They include authentication, Stripe subscriptions, admin panels, and billing portals. The same starter template, over and over. Let us build one with Claude in an afternoon. This is the most complex project in the series so far. Stripe’s webhook lifecycle, subscription state management, role-based access, and usage tracking all need to work together. A lot can go wrong. Total time: 5 hours 22 minutes. 7 prompts. Stripe webhooks took the most iteration. ...

Welcome to Part 3: Advanced Projects. We are done with quick builds and half-day apps. Now we tackle complex, multi-component systems. First up: a real-time chat application. WebSockets, authentication, rooms, typing indicators, online presence, message history. This is the kind of project that tests whether Claude can handle multiple moving parts that all need to work together in real time. Total time: 4 hours 38 minutes. 7 prompts. WebSocket auth was the hardest part. ...