What are the best practices for structuring web applications for scalability and maintainability?

A solid software architecture and some common sense can take you a long way. I really think separation of concerns and clear interfaces are crucial. If you mix UI, data, and network code, maintenance and refactoring become a nightmare. Build a strong core 'framework' that establishes the key global types, routing, and internal APIs. This will help keep everything organized and allows other modules to register their functionality cleanly. I also believe in centralizing everything to have a better grasp of data and workflow, especially for UI components—keep them simple, pass data down, and let events flow up.

There's no one-size-fits-all answer here; everything involves trade-offs. Think about what matters more for you—consistency or availability? Evaluate whether you'd rather use specific vendor solutions for quick setup or avoid vendor lock-in altogether. Understand the specific problems you're tackling before deciding on a solution—concepts like modularity and documented interfaces always hold value, but techniques like horizontal scaling and microservices depend on your unique challenges. I'd recommend "Software Architecture: The Hard Parts" for a deep dive into architectural patterns and their applications. For many startups, a modular monolith with a monorepo is often the way to go, but as companies grow, they might need to adapt to avoid scaling difficulties.

Check out this frontend implementation if you're looking for insights on scalability and maintainability: reactmvvm.org. It might give you some useful perspectives!

It's not just about the code; your infrastructure also needs to be ready for growth. You should choose something that can scale easily, like Vercel or Netlify, or consider a self-hosted solution that fits your needs.

Choosing between a modular architecture and a monolith isn't as simple as it sounds; modular monoliths are a solid middle ground. For managing dependencies and code quality, I stick to the KISS principle, test-driven development, and domain-driven design. They really help keep things organized as the project evolves.