Written by Juan Perez, Sr. Mobile Engineer at BetterEngineer
When the team at BetterEngineer reached out and asked me to share a story from my career, one particular project immediately came to mind: the first time I built an application designed to scale.
At the time, I had about six years of experience under my belt and felt confident in my skills. I’d built several apps before, but this project was a whole new level. The stakes were higher, the requirements more complex, and the end users far more numerous than anything I had dealt with before.
The project had its fair share of pitfalls, late nights, and embarrassing mistakes, but it also taught me some of the most valuable lessons of my career. Now, ten years in, I look back on that experience as a defining moment. So here are seven lessons I learned the hard way—hopefully, they’ll save you some headaches.
1. Design for Scale from the Beginning
When I started, I built everything like it was a quick prototype. It was a big mistake. While it’s tempting to focus on getting something functional up and running quickly, this mindset can lead to significant challenges down the road. Scaling is not something you “tack on” later—it needs to be baked into the foundation.
Consider factors such as load balancing, database optimization, and modular architecture early in the design process. These decisions will define how well your application can handle growth and increased demand. Retrofitting scalability into an existing system is like remodeling a house with the residents still living in it—messy and way more expensive.
To avoid repeating my mistake, ask yourself: What happens if user traffic doubles tomorrow? How easily can I add new features or services? Addressing these questions early will save you a great deal of time, effort, and frustration in the long run.
2. Simplicity Wins Every Time
I was tempted to flex my “elegant” coding skills by overcomplicating things. Don’t do it. Over time, I learned that complexity often creates more problems than it solves. A scalable app doesn’t need fancy solutions; it needs reliable, maintainable code. The simpler your design, the easier it is to scale and debug when things inevitably break.
So whenever you’re tempted to create a “clever” solution, ask yourself: Is this the simplest way to achieve the desired outcome? Can someone else understand and maintain this code without hours of explanation?
3. Performance Monitoring Is Non-Negotiable
Trust me, debugging in real-time when users are frustrated is not fun. Tools like New Relic, Datadog, or even a simple custom dashboard give you the visibility you need to see how your app is performing in the real world. You’ll want to keep an eye on things like CPU usage, memory, response times, and error rates. These metrics are like the vital signs of your app—they tell you if everything’s running smoothly or if something’s off.
It’s not just about avoiding crashes—it’s about catching small issues early before they become bigger problems. For instance, you might spot a slow database query or a memory leak while you're still building, rather than scrambling to fix it when users are already frustrated.
If I could go back, I’d make performance monitoring one of the first things I set up. It’s one of those things that’ll save you time and improve the experience for your users.
4. The Database Is Your Bottleneck Until Proven Otherwise
Databases will be your app’s Achilles’ heel if you’re not careful. My rookie mistake was assuming my database could handle anything I threw at it. As traffic grew, so did the cracks in my setup.
The solution? Start with a solid foundation: implement indexing to speed up queries, use caching wherever possible (Redis saved me more than once when response times lagged), and don’t hesitate to shard or replicate your database as your demands increase. Treat your database as a living system that needs constant care, and it’ll serve you well as your app scales.
5. Test As Your App Depends on It—Because It Does
Scaling brings a level of complexity that surfaces issues you’d never notice under normal conditions. I remember the time a harmless query that ran fine with 10 users brought the entire system down when 1,000 users showed up. It was a wake-up call: testing in controlled environments isn’t enough—you need to simulate real-world scenarios.
Load testing helps you understand how your application performs under expected user traffic, while stress testing pushes it beyond its limits to reveal breaking points. Chaos engineering might sound extreme, but intentionally introducing faults into the system can help you identify weaknesses before they become real problems. That way you ensure you’re prepared for anything scaling throws your way.
6. Your Team Is as Important as Your Tech Stack
No matter how skilled you are, you can’t do it alone. Building something scalable requires collaboration. Effective collaboration—whether through brainstorming sessions, code reviews, or task delegation—brings diverse perspectives to the table, leading to better solutions. Trust and communication within your team are the foundation for success. When everyone feels valued and aligned toward the same goal, it creates a synergy that’s hard to replicate with tools alone. Technology evolves quickly, but a strong team can adapt and overcome challenges together.
7. Expect Challenges—And Embrace Them
Looking back, building a scalable application was one of the most rewarding (and challenging) projects I’ve worked on. There will be moments when things go wrong—deployments fail, user feedback highlights unforeseen issues, or deadlines feel impossible to meet. In these situations, it’s easy to feel overwhelmed or frustrated.
Over the years, I’ve come to see these challenges as opportunities. Each problem, no matter how daunting at the time, has taught me something valuable—whether it’s a better way to architect a solution, the importance of clear communication, or how to stay calm under pressure. Scaling isn’t just about building an application that can handle growth; it’s about developing the resilience and mindset to grow alongside it. Every obstacle is a stepping stone to becoming a better engineer and creating better systems.
Building for the Future
What I’ve learned is that scalable systems aren’t built overnight; they evolve through careful planning, rigorous testing, and the willingness to adapt. The stakes may be high, but the rewards—both personal and professional—are worth the effort.
As you embark on your own projects, remember that scalability is not just a feature; it’s a commitment to building something that lasts. And while the process will have its challenges, those are the moments that define your growth as an engineer. Keep learning, keep building, and always aim for better.
If you’ve enjoyed this story, keep an eye out—my colleagues and I will be sharing more insights and experiences through BetterEngineer. Each project has a story, and we’re excited to share how we’re building great things together.
