What's the Best Approach to Building a Product that Can Easily Add New Features?

So you want to build a product that keeps evolving. Something that grows alongside its users, adapting to their needs, their whims, and maybe even their untold dreams. I get it. That’s the holy grail for anyone working in product development. A product that’s not only useful today but is designed to keep being useful tomorrow—in ways we haven't even thought of yet. It sounds like a tall order, but it doesn’t have to be.

If you run an outsourced software dev company, like I do at 1985, you know that clients often come to you with a vision. They want their product to be scalable, flexible, and, most of all, capable of growth—the kind of growth that allows for new features to be easily bolted on without a major overhaul. You want a product that feels almost alive, breathing and expanding as needs change.

But what does it really take to make that happen? Let's break down the best approaches to building a product that can easily add new features, and why taking the time to get this right up front saves you headaches—and saves your client’s money—in the long run.

Think Architecture Before Features

The first step is often the least sexy one: architectural planning. We’re not talking about the fun, flashy features you can show off in a demo. We’re talking about bones—the skeleton beneath the skin of your product. And if you want the ability to add features easily later, you’ve got to make sure you have the right architecture from the start.

There’s a concept called modular architecture. It’s exactly what it sounds like. Instead of creating a monolithic codebase where everything is tightly interconnected, modular architecture separates components into independent modules. Each module is like a Lego brick—a standalone entity that can be connected or disconnected without breaking the entire structure.

Consider microservices, for instance. Microservices have become somewhat of an industry standard when it comes to building scalable products. Instead of bundling everything into a single service, each feature exists as a separate service, independently deployable and maintainable. Uber switched to microservices architecture precisely because the traditional monolithic setup couldn’t support the rapid iteration and feature addition they needed.

In short, choosing a modular or microservices architecture at the outset means you're deliberately designing your product to grow. This is what makes it possible to add that shiny new feature six months down the line without touching 90% of the existing code.

The Hidden Pitfalls of a Monolith

I’ve seen teams try to be smart by focusing on rapid development rather than foundational architecture. They build an MVP in record time. They impress stakeholders. Everyone's happy, right? Not exactly. Six months in, when it's time to add new features, you realize that everything is tangled together like spaghetti.

Let’s say you’ve built a financial product and your client wants to add automated tax reporting. Easy, you think, until you realize that half of your new code touches the existing transaction feature, which in turn affects user authentication, and so on. Now adding a "small feature" is like playing Jenga with a skyscraper. One wrong move, and you could take down the whole stack.

That’s why avoiding a monolithic structure is critical. Think of it as future-proofing your product. A little planning at the start—making sure your bones are solid—means no late-night panic attacks when someone wants to tweak a feature.

Build With the Idea of Extensibility

After architecture, comes the concept of extensibility. Imagine your product as a house. You start with a simple two-bedroom. But you’re planning to have kids someday, so you make sure to design it with a large backyard where you could easily extend, or with a garage that could become another room.

In software, extensibility means building with hooks, endpoints, and enough wiggle room to accommodate future change. Think of APIs as critical arteries of your software. A well-documented API lets your product integrate with third-party services easily. APIs not only allow external integrations but also internal ones, providing easy touchpoints for new features.

Take Shopify, for example. It’s a platform built for extensibility. It offers an impressive number of APIs that allow developers to add new features, apps, and extensions. If a client wants their e-commerce store to link to a custom shipping provider, or add AI-driven personalization to product recommendations, the hooks are already in place. They don’t have to touch the core software—they just extend it.

The same goes for internal extensibility. If you’re using object-oriented programming (OOP), consider the potential for inheritance and polymorphism. Write your classes and functions in such a way that adding new behaviors doesn’t require reworking what's already there. This mindset will make the difference between a codebase that's a pain to manage versus one that invites growth.

Maintain Loose Coupling

Hand-in-hand with extensibility is loose coupling. Imagine you have a bunch of electrical appliances—a fan, a lamp, a coffee maker. If they all used one master switch, you’d be in trouble when you wanted to turn just one off. Instead, you want them to be independent—able to be replaced, turned off, or changed without affecting the others.

Loose coupling in code means each part of your system knows as little as possible about the other parts. Dependencies are minimized. Adding a new feature like a notification system, for instance, should ideally not require a single change to your order-processing logic. This is why dependency injection is so popular in modern frameworks; it allows you to manage dependencies in a way that maintains flexibility.

The principle of Separation of Concerns (SoC) is particularly important here. Each module, each component, should handle its specific task and do it well, without overlapping responsibilities. When you follow SoC, each part of your system becomes like an appliance with its own plug, ready to be swapped out or modified independently.

Prioritize Maintainability, Always

If adding a new feature feels like open-heart surgery—where every movement risks killing the patient—then something is wrong. Your code should feel like it’s alive, sure, but it shouldn’t feel like it’s about to flatline.

Maintainability is what makes adding new features manageable instead of a nightmare. Documenting your code is part of that, but it's also about structuring the code in a way that anyone, including your future self, can understand it.

Code Reviews: The Unsung Heroes

Code reviews are essential. I’ve worked with teams who think that once code works, it’s good to go. But a code review isn’t just about making sure something runs; it’s about ensuring that new code is maintainable, follows best practices, and doesn’t create dependencies that turn into bottlenecks later on.

Think about Airbnb. Their development process involves rigorous peer reviews where each feature addition is scrutinized for its long-term impact on maintainability. The result is a product that can evolve—not just because it’s designed to, but because every new piece is carefully integrated with the future in mind.

Tests: A Necessary Expense

Tests can feel like overhead, especially when you’re under pressure to deliver. But the right testing suite is like an insurance policy for your product’s future. Without it, even adding a single line of code can feel risky. With it, you’re able to iterate confidently.

Automated tests, unit tests, integration tests—they’re all parts of a well-tested codebase that will save you hours and hours when adding new features. Take the Netflix engineering team. They run extensive tests before rolling out even small changes, ensuring that new additions do not disrupt the platform's functioning. That’s the kind of investment that makes a product future-ready.

Test-Driven Development (TDD), while not always a perfect fit, can be a useful approach when building critical components. Writing tests before you write code forces you to consider the feature's use cases, edge cases, and expected behaviors, laying the foundation for reliable expansion down the line.

Focus on Developer Experience (DX)

Here’s something we don’t talk about enough—developer experience. If adding new features is painful for developers, your pace of growth will slow to a crawl. But if your system is easy to navigate, your developers will be happy, efficient, and able to keep adding value.

Imagine stepping into a foreign kitchen. There are no labels, no clear organizational logic. It takes you minutes just to find the salt. Now imagine stepping into a perfectly labeled, organized kitchen. You’re slicing and sautéing in no time. That’s the difference DX makes.

Part of improving DX is reducing cognitive load—making sure developers can easily trace logic, understand the flow of the code, and not get lost in complexity. It’s also about having high-quality tooling in place: linters, formatters, debuggers, CI/CD pipelines that work smoothly, and internal documentation that’s actually readable.

Google is known for its internal tooling that allows developers to move swiftly when adding new features. Tools that offer real-time error checking, automated builds, and comprehensive documentation make adding features less about struggle and more about creativity.

Balancing Technical Debt and Innovation

Lastly, there’s the eternal struggle between technical debt and innovation. You want to keep adding new features—that’s the fun part. But every time you take a shortcut to add something quickly, you accumulate technical debt that will come back to haunt you.

Adding new features without increasing technical debt means making hard choices. It means pushing back when a feature isn’t thought through, or when it’s clear that an architectural change is needed but stakeholders want it fast. This is especially challenging in an outsourced dev environment where clients want results—yesterday.

The key here is transparency. Explain to clients that adding a new feature quickly might mean sacrificing long-term flexibility. It’s a delicate conversation, but the more transparent you are, the more they’ll understand why cutting corners isn’t always the best option.

Netflix’s approach to technical debt is illuminating. They acknowledge its existence, measure its impact, and prioritize refactoring when needed. They know that in the long run, technical debt will slow feature velocity and that the trade-off isn’t worth it. They’ve been successful because they make intentional choices, balancing innovation with maintaining a clean, modular system.

Wrapping It Up: Building for the Long Haul

Building a product that can easily add new features isn’t about anticipating every feature request your client will have. It’s about building smart. It’s about laying the groundwork that makes growth natural, not painful. That starts with a modular, extensible architecture that’s loosely coupled and maintainable. It’s about testing, about considering the developer experience, and about making thoughtful choices to minimize technical debt.

At 1985, our approach to building products centers on flexibility—giving our clients not just what they need today but what they’ll need tomorrow. We’ve learned, often the hard way, that investing in these foundations isn’t just good practice—it’s the difference between a product that evolves and one that stagnates.

So if you’re planning to build something that grows, remember: the flash can come later. First, build solid bones, make it extensible, keep it loosely coupled, and above all, keep your developers in mind. Features will come. But without the right foundation, they might come at the cost of stability and sanity—something neither your team nor your clients can afford.