Legacy Code: Rewrite, Refactor, or Start from Scratch?

Discover the optimal approach to legacy code: rewrite, refactor, or start from scratch. Learn the pros and cons of each option, along with decision-making criteria to guide your choice. Optimize your codebase for performance, maintainability, and future growth.


When working with legacy code, it's inevitable to encounter challenges that may require a strategic decision: should you rewrite, refactor, or start from scratch? This blog post analyzes these options, providing actionable insights to guide your decision-making process.

Understanding Legacy Code

Legacy code refers to outdated software written in an obsolete language or using outdated technologies. While it may still function, legacy code is often difficult to maintain, extend, or upgrade. This can lead to performance issues, security vulnerabilities, and increased development costs.

Evaluating the Options

1. Rewrite the Code

Rewriting involves replacing the entire codebase with a new one.


  • Eliminates legacy code problems
  • Implements modern technologies and best practices
  • Provides a clean and maintainable codebase


  • Time-consuming and costly
  • Can disrupt existing functionality
  • May require retraining developers

2. Refactor the Code

Refactoring involves modifying the existing codebase to improve its structure, design, and readability.


  • Preserves existing functionality
  • Enhances code quality and maintainability
  • Can be done incrementally


  • May not solve all legacy code issues
  • Can be complex and time-consuming
  • Requires expertise in the original codebase

3. Start from Scratch

Starting from scratch involves building an entirely new codebase from the ground up.


  • Complete control over the codebase
  • Utilizes modern technologies and best practices
  • Eliminates all legacy code issues


  • Most time-consuming and costly option
  • May lose existing functionality
  • Requires extensive development effort

Decision-Making Criteria

The best option for addressing legacy code depends on the specific situation. Consider the following factors:

  • Code Quality: Is the legacy code significantly flawed or poorly written?
  • Maintenance Cost: Does the legacy code require frequent maintenance or updates?
  • Functionality: Is the existing functionality still essential or can it be replaced?
  • Development Resources: Are sufficient resources available for rewriting or starting from scratch?
  • Timeline: How urgently is the codebase improvement needed?

Best Practices

  • Conduct a thorough code analysis. Understand the extent of the legacy code issues and their impact on the system.
  • Consider a hybrid approach. Combine refactoring and code additions to address specific issues without a complete rewrite.
  • Test thoroughly. Ensure the modified codebase maintains expected functionality and meets quality standards.
  • Document the changes. Clearly outline the approach taken and any potential risks associated with the changes.


Rewriting, refactoring, or starting from scratch when dealing with legacy code is a strategic decision. By understanding the options and considering the decision-making criteria, you can make an informed choice that optimizes your system's performance, maintainability, and future growth. For expert guidance in overcoming legacy code challenges, consider Ottia's task-based outsourcing services. Our skilled developers specialize in code refactoring, modernization, and migration, helping you achieve your goals effectively and efficiently. Let’s begin the journey of transforming your codebase!

Tasha Tolmacheva
Backoffice & Suppliers

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