Legacy Modernisation: Pragmatism Over Perfection

In many circles, “Legacy Code” is treated as a dirty phrase. It’s the stuff engineering teams complain about in standups and use as an excuse for why features are late. But let’s look at it through a different lens: Legacy code is code that is actually delivering value to your customers today.

The challenge isn’t the existence of legacy code, but how we choose to modernize it.

The ‘Big Bang’ Rewrite Trap

The most common mistake I see as a Fractional CTO is the urge to throw everything away and start from scratch. A rewrite is rarely the answer. It’s expensive, it introduces new bugs, and it creates a “feature freeze” that can kill a company’s momentum.

A Pragmatic Approach to Tech Debt

Instead of a rewrite, we focus on high-impact, low-disruption strategies:

1. The Strangler Pattern

Incrementally replace parts of the system with new services. The legacy system continues to run while you slowly “strangle” it with modern architecture. This allows for continuous delivery and reduces risk.

2. People Over Process

Tech debt is often a symptom of team misalignment or outdated processes. To fix the code, you must first fix the culture. Are your engineers empowered to make architectural decisions? Is there a shared understanding of what “good” looks like?

3. Mentorship and Knowledge Sharing

Modernising a system is a great opportunity to level up your team. Pair programming and internal tech talks can turn a daunting refactor into a valuable learning experience.

Building for the Future

Modernisation isn’t just about changing a database or upgrading a library. It’s about building a foundation that allows your team to innovate faster.

Pragmatism over perfection. Always.