february, 2025

Legacy Code: Refactor or Rewrite?

In software development, dealing with outdated code—commonly known as legacy code—is just part of the reality for many companies. Over time technologies evolve and code that was once cutting-edge can turn into a source of challenges and obstacles.

For business owners outdated software is not just a technical challenge but a strategic decision point. As technology evolves, businesses must decide: should they invest in upgrading existing systems or start from scratch with a full rewrite? The right choice impacts costs, operational efficiency and long-term scalability.

Understanding Legacy Code

Legacy code is software that still supports critical business processes but is difficult to maintain, expensive to upgrade and prone to security risks. It may rely on outdated frameworks, lack proper documentation, or require specialized (and costly) developers to support it. These issues can slow down feature development, increase downtime, and reduce competitiveness.

Refactoring: Updating Without Rewriting

Refactoring is the process of restructuring existing code without changing its external behavior. The goal is to improve code structure, making it more readable, maintainable and scalable. The benefits of refactoring include:

Reducing technical debt

Improving code quality decreases the likelihood of errors and simplifies maintenance.

Enhancing performance

Code optimization can lead to better application efficiency.

Improving security

Identifying and eliminating vulnerabilities during refactoring reduces security risks.

Rewriting Code: A Fresh Start

Rewriting code from scratch may seem like a radical step, but in some cases, it is the most effective approach. The benefits of rewriting include:

Adoption of modern technologies

The ability to use new programming languages, frameworks and libraries.

Improved architecture

Designing a system based on modern principles and best practices.

Eliminating accumulated issues

Removing outdated solutions and temporary fixes built up over the years.

However, refactoring requires significant time and resources. Additionally, without proper testing, there is a risk of introducing new bugs.

Cost-Benefit Analysis

Before deciding between refactoring and rewriting, a thorough analysis is essential. Key factors to consider include:

1

Current code condition

Is it stable and maintainable?
2

Business requirements

Is rapid feature development required?
3

Resources

Are the necessary time and budget available
4

Risks

What are the potential consequences of each approach?

How Do You Decide?

If you’re on the fence, use this checklist. If you want to test yourself, get a free checklist by sending us a request. Check your spam folder if the email hasn't arrived.

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In many cases, a hybrid strategy works best—refactoring core functionalities while gradually replacing outdated components. This minimizes risks while ensuring business continuity.

Legacy code is more than a technical issue; it’s a business decision that affects growth, security, and profitability. A well-planned approach—whether refactoring, rewriting, or a mix of both—ensures that your software remains a competitive advantage rather than a bottleneck.