Rewriting vs Refactoring Code: How To Navigate The Two

As a software engineer, you’re likely to encounter situations where you need to improve or optimize an existing codebase. When deciding how to approach this type of task, it’s important to understand the differences between rewriting and refactoring. At some point you’ll need to analyze rewriting vs refactoring code — and you’ll need to move forward down one of these paths.

In general, rewriting is the process of completely replacing an existing codebase with a new implementation. On the other hand, refactoring involves making incremental changes to an existing codebase with the goal of improving the overall quality and maintainability of the code. Both approaches have their pros and cons and the decision to refactor or rewrite should be made pragmatically.

Throughout this article, I’ll share the benefits and drawbacks of each approach to help you decide which one is right for your project.

What’s In This Article: Rewrite vs Refactor

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Exploring Refactoring Code

Refactoring code involves making improvements to the existing codebase (ideally) without altering its overall functionality or performance. Common examples of refactoring include cleaning up code for readability and organization, removing redundancies, and general optimization. Refactoring is useful in situations where the codebase is functional, but has areas that could use improving to make ongoing development more efficient.

The Benefits of Refactoring Code

Refactoring is beneficial in multiple ways. First, it maintains the overall functionality of the codebase while also making it more efficient. This saves time in the long run, as developers are able to work on the latest features without being slowed. Second, refactoring can improve overall code quality, making it easier to maintain going forward. This can improve the overall performance and scalability of the application.

Knowing when to refactor is just as important as knowing how to refactor. A key indicator that refactoring is necessary is noticing code smells, which are small indicators that the code could use some cleaning up or optimization. These issues may include duplicated or confusing code, large files with too many dependencies, lengthy or convoluted functions, and more.

To implement this properly, techniques for organizing and optimizing code are often used. These are common programming patterns and best practices that can be used to simplify and optimize code. These could include using inheritance, reducing function parameters, and proper commenting. By identifying and resolving code smells, developers can ensure that the codebase remains efficient, scalable, and maintainable.

The Risks and Pitfalls of Refactoring Code

One of the primary risks of refactoring is the potential for introducing bugs into a working system. Even small changes in a complex codebase can have unexpected consequences. Without comprehensive testing, refactoring can lead to system instability or functional errors. This risk is particularly high in legacy systems, where test coverage is slim or –even scarier– completely missing.

Another potential drawback is the time and resources required. Refactoring can be a time-consuming process, especially in large or complex codebases. It can divert development resources away from new feature development or critical fixes, even blocking landing solutions to these until the refactoring effort is complete. This trade-off can be a difficult balance to strike, especially under tight deadlines or limited resources.

The urge to ‘perfect’ the code can lead to over-engineering, where developers spend too much time iterating on the code. This can lead to a scenario where the cost of refactoring outweighs its benefits. So it’s tremendously important that there’s alignment on what the goal of the refactoring is. Remember, customers don’t care how neat and tidy your code is — you do! And after some point, there are diminishing returns for being able to ship value to your customers more effectively.

Refactoring also demands a high level of skill and understanding of the existing code. Misunderstanding the original intent of the code can lead to changes that may alter its functionality, leading to subtle bugs that are hard to trace and fix. This is particularly challenging in team environments, where different developers might have varying levels of understanding of the codebase.

Let’s Chat About Rewriting Code

Rewriting is the process of completely overhauling an existing piece of software and starting from scratch. While this sounds like a daunting task, there could be benefits to rewriting code when appropriate. And of course, associated risks to consider before diving head-first into blowing away your codebase in favor of a green field.

The Benefits of Rewriting Code

In some cases, refactoring can lead to more problems and can be a waste of time. In situations where the existing codebase has significant issues or major pain points, a rewrite can be the most effective solution. By starting fresh, developers can have more flexibility in choosing the best tools, frameworks, and architecture for the project.

One of the biggest advantages of rewriting over refactoring is better flexibility from the perspective of the programmers. With a rewrite, developers can start with a clean slate and choose the best tools and frameworks for the project. They can also make fundamental architecture changes that may seem far less feasible with refactoring. This can lead to better scalability and easier maintenance down the line.

Another advantage of a rewrite is improved scalability. With a fresh start, developers can design the architecture to be more scalable, enabling the application to handle growth and increased traffic more effectively. By starting over, developers can focus on building the application with extensibility in mind. This can help reduce complexity and improve maintainability down the line as the application grows.

And… Maybe Why We Shouldn’t Fully Rewrite Code

One of the most substantial risks of a full rewrite is the loss of knowledge embedded in the existing code. Even flawed, legacy code often contains solutions to problems and nuances that have been discovered and addressed over years of development. A full rewrite risks losing this institutional knowledge, potentially reintroducing old bugs or failing to meet undocumented requirements.

Additionally, rewrites often suffer from underestimation of time and resources. Starting from scratch can seem straightforward initially, but the complexity and scope of the project can quickly escalate. This can lead to prolonged development times, significant delays in releasing new features, and increased costs. I have lived this MULTIPLE times.

Another drawback is the potential disruption to users. A rewrite can mean a long period without new features or improvements as the development team focuses on rebuilding existing functionality. This can frustrate users and stakeholders who are awaiting new features or improvements that are on hold during the rewrite.

Rewrites also carry the risk of never reaching completion. Due to the extended development times and shifting business priorities, the project might get canceled or indefinitely delayed. This can result in a substantial waste of resources with little to show for the effort since it’s not done incrementally like refactoring code.

When to Rewrite

While rewriting code is not always necessary or practical, there are situations where a rewrite may be a reasonable course of action. I have a bias for avoiding rewrites because I think that some of the benefits we looked at don’t translate into reality as clearly. However, some signs that a rewrite may be beneficial include:

  • The existing codebase is highly complex and difficult to maintain.
  • The codebase has inconsistent architecture or design patterns.
  • The application has significant performance issues.
  • The existing codebase is written in a language or framework that is no longer supported or widely used.

Before beginning a rewrite, it’s important for developers to carefully plan and outline the scope of the project. This helps ensure that all stakeholders are aligned to minimize the risks of scope creep. By taking the time to plan and execute a rewrite correctly, developers can create a more efficient, effective, and scalable product.

Are you interested in boosting your refactoring skills? Check out my course on Dometrain:
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Choosing Between Rewriting vs Refactoring Code

As a software engineer, it’s important to recognize the key differences between rewriting vs refactoring code. While both approaches require time and resources, they each solve unique problems. When deciding which path to take, it’s important to analyze the project timelines, resources, and requirements to ensure successful execution. Let’s look at two hypothetical examples where we might pick one option over the other!

Refining a Legacy E-Commerce Platform

Imagine an e-commerce platform, “ShopRight”, that has been operational for several years. The platform has a large user base and a significant volume of daily transactions. However, the developers have noticed that the codebase has become somewhat unwieldy, with certain modules being overcomplicated and difficult to maintain.

The Challenge: The ShopRight platform experiences occasional performance issues, and the development team finds it increasingly challenging to implement new features due to the convoluted code.

Why Refactor: In this scenario, opting for refactoring makes sense for several reasons. Firstly, the platform is fundamentally sound and successful, so a complete overhaul isn’t necessary. Secondly, a total rewrite could disrupt the ongoing operations and risk the stability of the platform, which is crucial for maintaining customer trust and business continuity. Lastly, incremental improvements through refactoring can be done alongside regular updates, thereby minimizing disruptions and utilizing the existing knowledge embedded in the current codebase.

Approach: The team decides to systematically refactor the codebase, starting with the most troublesome modules. They introduce unit tests to ensure that functionality remains consistent, and they clean up the code to improve readability and maintainability. This approach allows ShopRight to maintain its operational stability while gradually improving the codebase’s efficiency and scalability.

Overhauling an Outdated Inventory Management System

Consider “StockGenius”, an inventory management system built a decade ago using technologies that are now outdated. The system is slow, not user-friendly, and lacks integration capabilities with modern e-commerce platforms and databases.

The Challenge: StockGenius is struggling to keep up with the requirements of modern inventory management, like real-time updates and integration with diverse sales channels. The existing codebase is not only outdated but also rigid, making it difficult to adapt to new technologies or to scale according to current business needs.

Why Rewrite: In this case, the team decides that a full rewrite is the better option. The current technology stack is so outdated that updating individual components would be like putting new wine in old bottles. The architectural limitations of the original system mean that it cannot easily be incrementally transformed to meet modern standards. A rewrite would allow the development team to utilize modern tech and design an architecture that’s scalable, flexible, and capable of integrating with various platforms.

Approach: The decision is made to develop a new inventory management system from the ground up, using modern development frameworks and methodologies. While this requires a significant investment of time and resources, the result is a state-of-the-art system that is well-equipped to handle the current and future demands of inventory management. The new system, “StockGenius 2.0” (If you watch my videos you know I’m bad at naming things) is birthed to address the drawbacks of the legacy one.

Summarizing Rewriting vs Refactoring Code

After discussing the benefits and drawbacks of both rewriting and refactoring, it’s clear that each approach has its own unique advantages. Refactoring is often (but not always!) faster, easier, and less risky, making it a great option for smaller-scale improvements. On the other hand, rewriting code can provide better scalability, flexibility, and maintainability, which may be helpful for larger-scale changes.

Making the right choice between rewriting vs refactoring code can be difficult, but it’s important to weigh the pros and cons of each approach and consider the specific needs of your project. By doing so, you can optimize your efforts, minimize waste, and achieve better results.

Ultimately, understanding when to choose between rewriting and refactoring is a critical skill for any software engineer. By using the tips and techniques outlined in this article, you can become a more effective and efficient developer, delivering better code and more value to your customers.

Remember to check out my course on Dometrain: Refactoring for C# Devs if you want to skill up on your refactoring! If you’re interested in more learning opportunities, subscribe to my free weekly newsletter and check out my YouTube channel!


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    Frequently Asked Questions: Rewrite vs Refactor

    What is refactoring and when is it beneficial?

    Refactoring is the process of improving existing code by optimizing it for clarity, extensibility, and maintainability. It is beneficial to refactor code when it contains code smells or is difficult to modify. Refactoring can also improve code quality by eliminating redundancy, increasing readability, and improving performance.

    What are the advantages of refactoring over rewriting?

    Refactoring is advantageous over rewriting because it maintains the existing functionality of the code, saving time and resources. Refactoring also improves the quality of the code without altering the core functionalities of the codebase. This helps to reduce risk, as well.

    When is it best to refactor code?

    It is best to refactor code when it has code smells, is difficult to modify, or has redundant code. Techniques like automation, code reviews and technical debt management can assist in identifying when a codebase requires refactoring.

    What is rewriting and when is it beneficial?

    Rewriting is rewriting a codebase from scratch. This approach is beneficial when the codebase has major issues and is difficult to maintain, scale, and add new features to. Additionally, rewriting code can improve its flexibility and scalability, allowing for easier maintenance with fewer bugs.

    What are the advantages of rewriting over refactoring?

    Rewriting allows for higher flexibility and scalability in the code, leading to quicker iterations and easier bug fixes. Additionally, since the new codebase is written from scratch, it is easier to add new features and functionality, without the constraints of the old codebase.

    When is it best to rewrite vs refactor code?

    It is best to rewrite vs refactor code when the codebase has major issues such as outdated technology, architecture problems or severe performance issues. This gives an advantage to start from scratch and avoid carrying forward technical debt issues that can arise with refactoring.

    How do you choose between rewriting and refactoring?

    Choosing between rewriting and refactoring comes down to considering a few factors, including the scope of the project, total available time and resources, and the primary goals for the system. For smaller projects, refactoring may be the more efficient approach. However, for larger projects, a rewrite may be more efficient. This can be balanced by considering the project timelines, requirements and risks associated with the approach chosen.

    What are the key considerations for executing a rewrite or refactoring approach successfully?

    Essential considerations are to weigh the impact on the performance, functionality and cost of the system. Successful execution also requires a plan for codebase testing and the willingness to automate low-level and repetitive tasks to limit the amount of time devoted to automation. When there’s significant resistance to change, its use must be communicated efficaciously and concerns must be addressed in order to increase confidence in the new codebase.

    What is the cost comparison of refactoring vs rewriting?

    The costs associated with refactoring are typically lower than those associated with rewriting. Refactoring only involves optimizing and improving specific areas of the codebase, whereas rewriting requires that the whole codebase is re-written from scratch. This increases the risks as well as cost/s of a rewrite.

    How can I choose the right path for rewrite vs refactor for my project?

    The right path for a project is primarily determined by the goals to be achieved, the existing level of technical debt, and a consideration of the resources, timeline and expertise necessary to implement the change. Conducting initial research can also assist the development team in identifying a project’s critical pain points.

    author avatar
    Nick Cosentino Principal Software Engineering Manager
    Principal Software Engineering Manager at Microsoft. Views are my own.

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