Software engineering, Startups, Product management
The rewrite trap: How it kills startups and what to do instead.
For startups racing against time and money, rewriting code can be a self-inflicted wound draining resources and stalling progress when you can least afford it. Instead continuous refactoring outlined in Martin Fowler’s book: Working Effectively with Legacy Code is a better way to deliver value and maintain momentum. In this article I explain what causes startups to rewrite, why it is dangerous and I provide a better approach to solve the problems.
Appeal of a rewrite
Early-stage code is often rushed and messy because startups prioritize delivering a working product to the market as quickly as possible. There is rarely enough time or resources to write proper tests, let alone design the perfect software architecture. Additionally, the problem domain is often not fully understood, leading to an initial codebase built on assumptions that may change as the product evolves. This creates a system that reflects the startup's early uncertainties rather than a well-defined, scalable foundation. Developers are often eager to fix the mistakes of the past, believing that starting fresh will make the product better and development faster.
Another common issue is that rapid scaling of the product overwhelms the original architecture. The code may become inefficient, consuming excessive resources, while new use cases lead to a proliferation of code paths, making the system increasingly difficult to maintain. Additionally, CTOs often feel pressured to adopt new technologies and frameworks that promise greater scalability and performance, further complicating the situation.
Why rewrites are dangerous
Rewrites are dangerous for many reasons:
- Time sink Rewriting a codebase takes months (or even years) during which no new features or value are delivered to customers. In startups, where time-to-market is critical, this delay can be fatal.
- Lost knowledge Existing code contains business logic and insights accumulated over time. Rewrites often overlook or misinterpret this knowledge, leading to functionality gaps and the introduction of new bugs.
- Customer impact During the rewrite, users may feel abandoned as bugs go unfixed and new features are not delivered. This creates an opportunity for competitors to catch up and position themselves as a viable alternative for your customers.
- The second system syndrome Introduced in Fred Brooks' book The Mythical Man-Month, this concept explains the tendency to replace a small, successful system with an over-engineered and overly complex one. This often results in higher maintenance costs and slower feature delivery.
A better alternative: effective refactoring
Effective refactoring is taking small, deliberate steps to improve the code while keeping it functional.” This approach emphasizes incremental improvements to the existing codebase without changing its external behavior. It is more flexible because it allows the company to continue delivering value while simultaneously improving code quality. Institutional knowledge is preserved since it is embedded in the legacy code, and risks are minimized by making small, testable changes rather than undertaking large, untested rewrites. It has the following key practices:
- Add Tests First Before making any changes, ensure you add unit tests around the legacy code to protect existing functionality. Tests serve as a safety net, allowing you to refactor with confidence and quickly detect if something breaks during the process.
- Work in Small, Safe Increments Instead of attempting large, sweeping changes, focus on making improvements in isolated areas of the codebase. This reduces the risk of introducing system-wide issues and ensures that changes are manageable and reversible if needed.
- Isolate Pain Points Identify and prioritize the most problematic or high-complexity areas of the code. By focusing on these pain points first, you can deliver the greatest impact with minimal disruption, rather than getting bogged down in a complete system overhaul.
- Continuously Refactor While Adding Features Refactoring should be an integral part of your development process. As you add new features, take the opportunity to improve the surrounding code, ensuring that the codebase evolves and becomes easier to maintain over time.
When a rewrite (if ever) is justified
There are rare cases where a rewrite might be necessary. For example:
- An Entangled Codebase The codebase has become so complex and intertwined that even small changes are nearly impossible without breaking functionality.
- Outdated and Unsupported Technology The technology stack is no longer maintained, making it impossible to scale, fix bugs, or integrate new features.
Even in such extreme cases, a rewrite should follow a contained strategy to minimize risks. How can this be achieved? Develop the new system alongside maintaining the old one to avoid a complete halt in delivering value to customers. This ensures the existing system continues to function while the new one is being built. Last but not least instead of launching the new system all at once, deliver small, functional pieces incrementally. This allows for testing, feedback, and adjustment along the way, reducing the risk of a total failure.
Conclusion: focus on delivering value
Rewrites may seem like an attractive solution to messy code, but for startups, they often lead to wasted time, drained resources and lost opportunities to deliver value to customers. In a world where time-to-market is critical, sacrificing progress for a complete overhaul can be fatal. Effective refactoring offers a safer, more practical alternative by taking small, deliberate steps to improve the code while preserving its functionality. This allows startups to maintain momentum, retain institutional knowledge and continue delivering value to customers without introducing unacceptable risks. When faced with a messy codebase, resist the temptation to rewrite and instead start making incremental improvements.
By focusing on refactoring, startups can build a solid foundation for growth while continuing to deliver value to their customers. Remember, it’s not perfection that drives success but progress.