But remain independent.
Architecture determines optionality. The way things connect today decides what you can change tomorrow.
“What happens when you need to change one thing?”
The answer reveals everything about how your systems are architected.
You know it's not simple. That one change touches three other systems. Testing takes longer than building. And you're not even sure what else might break.
That's what happens when systems are integrated. There's another way to connect things.
Systems merged together
How it looks:
Direct connections between components. Data flows through shared interfaces. One database serves multiple purposes.
The appeal:
Quick to build initially. Everything talks to everything. Feels efficient.
The cost:
Systems become dependent on each other. Change one thing, test everything. Upgrading requires coordination across the entire system.
Systems work together but remain independent
How it looks:
Clean boundaries between components. Standard interfaces. Each piece can operate independently.
The investment:
Takes more thought upfront. Requires designing for separation. Feels slower initially.
The payoff:
Change one thing, only that thing needs testing. Upgrade components independently. Replace parts without rebuilding everything.
Fix Perspective
If your systems are already tangled, you're living with the cost of integration every day. Every “simple change” that isn't simple. Every upgrade you can't do. That's the architecture speaking.
Enhance Perspective
If you're building something new, you have a choice. Build integrated and you'll move fast initially, then slow down as complexity grows. Build modular and you'll invest more upfront, then move faster forever.
The difference isn't visible when you're building.
It becomes obvious when you need to change something.
Two scenarios. Same type of change. Completely different experience.
Request: “We need to update how payments work.”
Request: “We need to upgrade the AI model powering our agent.”
Whether you're working with existing systems or starting fresh, the principle is the same: systems that work together but remain independent. The approach differs based on where you're starting.
You probably have systems you can't replace. Maybe the ERP your entire finance team knows. Maybe the CRM with years of customer history. Maybe something custom that just works.
The choice isn't replace or accept. There's a third option.
Build INTO
Customize the existing system. Add features inside it. Become dependent on its architecture, its limitations, its upgrade cycle.
You inherit every constraint the system has.
Replace
Rip out the old system. Migrate everything. Retrain everyone. Hope nothing breaks that you didn't know about.
High risk. Embedded knowledge gets lost.
Build AROUND
Add capability alongside. Connect at the edges. Existing system keeps doing what it does. New system adds what's missing.
Your team keeps using what they know. You get the new capability.
You're creating something new. You have choices that established systems don't.
Clean interfaces from the start
Define how components talk to each other before building them.
Independence as architecture
Each piece can run, test, and deploy independently.
Optionality built in
Want to swap the AI model? Change the data source? The architecture allows it.
Fix Perspective
Building around requires modular thinking. Clean interfaces. Clear boundaries. The ability to connect without becoming dependent.
Enhance Perspective
Building modular from day one is an investment. It takes more thought upfront. But it pays dividends every time you need to change something.
Design for independence. Build for change. Create optionality.
For the complete framework on building around existing systems, see Build Around, Not Into.
You've probably had that moment. A better tool exists. You can see it would solve the problem. But switching would mean rebuilding everything that touches it. So you don't switch.
The upgrade is available. You know you need it. But you can't risk breaking what works. So you stay on the old version. Another year passes.
That's what it costs to be locked in.
A better AI model launches. You can see it would improve your capability. You swap it in. Test the interface. Deploy. Done.
That's what it means to have optionality.
Found a better payment processor? A more capable AI model? Swap it without touching everything else.
New version available? Upgrade one piece. Test it isolated. If something goes wrong, roll back that piece.
Need new capability? Add it alongside what exists. Connect it at the edges. You're not rewriting, you're extending.
Fix Perspective
Every time you can't upgrade because it would break everything. Every time you can't switch because you're too deep in. That's the compound cost.
Enhance Perspective
Every time you can swap a component without fear. Every time you can upgrade without coordination. That's the compound benefit.
The question isn't whether modular architecture takes more thought upfront.
The question is whether you want to pay the cost of lock-in forever, or invest in optionality once.
Whether you're untangling existing systems or building something new, we start with the architecture.
Direct answers to what founders and CEOs ask about modular design, tight coupling, and building for change.
No. That's how tightly coupled software works. When systems are woven together instead of connected through clean interfaces, changing one thing means testing everything. A two-week project becomes two months because payment code is tangled with order processing, which shares data with inventory, which triggers notifications. Loosely coupled systems work differently. Each component has clear boundaries. Change one thing, only that thing needs testing. The difference isn't visible when you're building. It becomes obvious when you need to change something. Research shows tightly coupled architectures were designed for low rates of change. Modern businesses need the opposite.