Sometimes your clients might come to you with an existing source code that is not running efficiently and has lots of bugs. Your developer team is trying hard to fix the issues, but the debugging is challenging in the existing code. Then, developers find that it’s easier to rewrite the code from scratch than to spend a huge amount of time in fixing the bugs in the software whose code has not been written efficiently. But, at times, choosing to rewrite the code from scratch turns into a mess. It is a time-consuming process and can bring dissatisfaction to your customers. To help you with this, we have listed some useful tips on how to go about rewriting your code.

1. Know when to rewrite the code

Before rewriting the code, you should first check if the software (whose code you are rewriting) is still maintainable (meaning fixing the software defaults and updating its functionalities as per user’s requirement) or not.

There is no need to rewrite the code from scratch if

  • You can improve your software performance or correct its issues by repairing its faulty components.
  • You can add new modules and functionalities to the existing code in order to meet the new demands of your customers.

When to rewrite the code?

You should go for a complete rewriting of code only if you feel your software can no longer be maintained. Here are the reasons why your software is not in a maintainable state-

  • Its compatible hardware is no longer available.
  • The software is so tightly coupled that it becomes hard to segment its modules into chunks and to add new modules into it.
  • Its tools and techniques have become obsolete.

2. Understand the difference between rewriting and refactoring

To determine if your software requires code refactoring or code rewriting, you should first understand the difference between these two.

Difference between code refactoring and code rewriting

Code refactoring vs Code rewriting

It means restructuring the existing code without changing the key functionalities of the software.

It means complete rewriting of code from scratch. It doesn’t change the end result of the code. It changes the end result of the code. It improves the readability and flexibility of the code and reduces dependencies within the code base, making it easier for developers to modify the code in the future.It is usually done to correct the defect in the software.

While refactoring the code, the system should work the same way as it was working before. Due to this reason, it requires a huge amount of debugging and testing. And, while rewriting the code, the technology, prototypes, and architecture are completely free from legacy limitations. You should go for code rewriting if you want a complete change in the technology stack.

The chaos you face while rewriting and refactoring the code.


The green line in the graph shows how chaos changes with code refactoring.The black line in the graph shows how chaos changes with a complete rewrite.

From the given graph, we can depict that:

While code refactoring:

  • Chaos is increasing after every step of refactoring, but later the chaos decreases and application becomes stable.
  • There are many releases before the final release, enabling the product to evolve faster. Eventually, the final product will meet the customers’ requirements.
  • It is required to keep the system stable and working all the time.

While code rewriting:

  • During the rewriting phase, the chaos is constant but significantly increases after the final release of the product.
  • Stabilization period is longer, and the final release of the product is faster.

When should you consider rewriting over refactoring?

  • If cost is your concern because restructuring the code is more expensive than doing a complete rewrite.
  • If the debugging process becomes challenging.
  • If you want a complete change in software technology and its architecture.

3. Understand the associated risks

To rewrite an application, you need an experienced development team that can understand and interpret the existing software logic and then rewrite them in a new legacy system. You also need to translate your data and databases according to the new code base. After that, there will be a lengthy user testing process. Sometimes a full-scale rewrite of your software puts your business at risk. Ask the following questions to figure out if rewriting the code for your software is good for your business or not:

Question no. 1 why do you want to rewrite the software?

Question no. 2 What changes have you made in the software development process to make your product better than its previous version?

Question no. 3 Do you have a clear idea about all the functionalities and features of your existing software?

Question no. 4 Do you have test cases for the new features?

Question no. 5 What will you do if the new version of the product has defects?

Question no. 6 Do you need to migrate data from the old system to the new legacy system? If yes, then how will you do that?

Question no. 7 Will the existing developers be performing the rewriting task? If yes, then what changes have you made to help them do a better job?

Question no. 8 If you are hiring a new development team, then will they be able to coordinate well with original developers to understand the existing code?

Question no. 9 Can developers approach the customers to understand their technology needs?

Question no. 10 How will you deploy your new written code?

Answering these questions will help you uncover the risks and challenges associated with a complete rewrite. There will be fewer chances of delays, errors, cost overruns, and data loss.

4. Decide whether to rewrite on-premises or to outsource

Before deciding whether to rewrite the code at your own premises or to outsource, ask the following questions:

  • Are your existing tools and application packages at your premises good enough to meet technological needs?
  • Do you have time, skills, and expertise to rewrite the software on-premises?

If any of the answers to these questions is no, then it’s better to go for outsourcing. But, managing outsourced team requires special skillsets and expertise. Read the following to know how to master the host of challenges while managing an outsourced team.

How to manage the outsourcing team?

  • Define your requirements precisely and clearly.
  • Assign the modules that you want to be developed by the outsourcing vendor.
  • Plan a meeting with their development team for seamless integration of codes in your new code base.
  • Plan a meeting with their quality assurance (QA) and quality control (QC) teams to determine best QA and QC procedures.
  • Monitor the timelines you have given to them.
  • Give them regular feedback about the code modules or features they have built.

Selecting the best-outsourced team for your product will provide your customers with superior services and increase your business productivity. But choosing the best outsourcing partner is a complex task because if you choose a company that is not experienced or does not know how to serve your business needs, then the result could be disastrous for your company.

What factors to consider while choosing your outsourcing partner?

  • Reliability: Check the experience of the company and its history.
  • Project experience: Check if they have experience in similar projects that you are about to outsource to them.
  • References: Ask them for at least three references to see if their clients are satisfied with their work.

Set properexpectations for cost

Most of the time, the cost to rewrite the software goes to 5, 7, or even 10 times higher than the estimated cost.

To set proper estimation for cost, look at the following hidden costs you need to include:

  • Account for the features that the maintenance team will add later once the development team rebuilds the software.
  • While rewriting the code, you need to migrate from the old legacy system to the new system. Add this migration cost into your overall estimate.
  • Add the maintenance cost of your old system that needs to be run in parallel while you are rewriting the code.
  • Account for the new demands of your customers (that can arise anytime) for the product that requires you to include new features.
  • Add the cost of hiring new developers.

What to do after rewriting the code?

Once you rebuild the software, keep the following things in mind to keep your software up and running:

  • Devote a large portion of your development time on defects and issues.
  • Allocate time to adding new features.
  • Plan to spend time upgrading methodologies, designs, and operating systems.