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Technical Debt Reduction in Legacy Systems: How to Do It Efficiently

When you prioritize quick delivery over good code quality and organization, the result is technical debt. You are trading off long-term benefits over short-term results.

According to a Stepsize survey, 58% of companies don’t have a process to reduce technical debt, despite 60% of engineers warning about its negative impact on business. Code debt, especially that which is deliberate, can be super dangerous for your software product! 

Technical debt makes working on older systems harder than necessary. It’s an unpleasant reality for devs and business owners. More often than not, the cost of technical debt significantly increases over time; which means the earlier your organization starts to deal with these loans in your codebases, the better. 

Legacy systems are no stranger to technical debt and have a large pile of unpaid technical debt which must be reduced to make updates easier and faster, as well as increase the quality of the product. 

Read on to learn more about technical debt, common causes, best practices to tackle this debt, and solutions for technical debt reduction with legacy codebases.

Understanding Technical Debt in Legacy Systems

What is technical debt in legacy systems? Legacy code has been around for too long. Technologies, user needs, project requirements, and programming techniques are constantly evolving, and so should our codebases as well.

Technical debt in legacy systems refers to the amount of extra work required to effectively modernize these legacy codebases – making them maintainable, and scalable.

Spendings on technical debt according to the McKinsey survey | ModLogix

Technical debt is inevitable in legacy systems for the following reasons outlined:

  • Legacy code is relatively old, built on somewhat out-of-date technologies that may limit growth.
  • Legacy code might have been implemented hastily and unprofessionally. 
  • The legacy code was built by hundreds of developers, each bringing a different programming technique – making the code unmaintainable.
  • The absence of a suite of automated tests in legacy code is another major technical debt hole that needs fixing. 

The major problem with technical debt in legacy code is the maintenance cost. Technical debt makes it so difficult and expensive to add new features to legacy code or change existing modules without breaking the system. No business owner wants to overpay for their software.

Common Causes of Technical Debt

What are some of the main causes of technical debt in legacy code?

Causes of technical debt in legacy systems | ModLogix

1. Design decisions

The design decisions that were made when your developers wrote the code for the first time are a leading cause of the current technical debt your codebase is facing. These decisions may have been good ideas at the time, but they may no longer be appropriate or even safe for present times. 

For example, maybe your developers chose to store everything in one database table when they wrote your system because it was easier than splitting things up. Yet today, putting all that data in one database is obsolete.

How to avoid technical debt? Start by making thoughtful design decisions at the planning stage of the development process. Future planning is essential for reducing the amount of technical debt that will be buried in your codebase over time.

2. Poor communication of project requirements

Code that is implemented without a clear understanding of the requirements will result in technical debt. This can be caused by a misunderstanding or miscommunication among stakeholders, a requirement that wasn’t properly documented, or the absence of documentation at all. While among the key benefits of legacy code documentation are the availability of the project specifications and faster releases or bug fixes.

3. Low test coverage

Technical debt is also caused by poorly written tests that do not cover important functionality, perhaps because they were written before the actual functionality was created (or maybe never written at all as is the case with legacy codebases). Maybe your team did not have enough time to write unit tests, and now your codebase has lots of bugs that need fixing before it can be refactored into something more modern.

4. Poor development practices

All businesses work with deadlines. Your need for a final product to be delivered as quickly as possible lures developers into ignoring best practices, and prioritizing speed instead of code quality. The obvious outcome is technical debt.

5. Team lags behind

When your team fails to learn, upskill, and catch up with new technology, the result is technical debt. Technologies move so fast; over 3-5 years, the technologies on which your systems are built become obsolete. Your in-house developers should be in the capacity to learn these new technologies and programming techniques, to modernize your legacy codebases. Investing in your team is one of the best investments you can make as a business.

In summary, technical debt is dangerous for the following reasons:

New features become more difficult to add.

  • Features that should be simple become complex and time-consuming.

  • When a new feature requires changes in multiple parts of the system, the cost of change increases exponentially.

  • New features take longer to build and can’t be used until they’re finished.

  • Testing becomes more difficult and expensive as more complex features are added to the system.

  • The code will increasingly be harder to understand and debug, which slows down development even further.

3 Major Benefits of Reducing Technical Debt

If your product must scale and improve in quality, your team must work hard toward eliminating code debt from your legacy codebase.  The benefits of reducing technical debt in legacy codebases can be broken down into three major categories:

Key benefits to reduce technical debt | ModLogix


Reducing technical debt makes it easier for your team to produce new features, fix bugs, and ship quality software. It also improves their morale, as they can deliver more value faster.

Product quality

A well-designed system can accommodate a larger feature set than a poorly designed one (see Conway’s Law). Therefore, reducing technical debt can help you build better products that are less prone to bugs and security vulnerabilities.

Maintainability and scalability

A well-designed codebase is much easier to expand and maintain than an ill-conceived one. Reducing technical debt reduces the cost of future maintenance by making it easier for new developers to understand your codebase and adopt new technologies.

Another important benefit of reducing legacy code is the fact that it saves your business money and resources in the long run – money that would otherwise be channeled towards writing a new codebase.

Effective Technical Debt Reduction Strategy for Legacy Code 

According to an Accenture survey, 72% of C-suite executives state that their legacy systems hamper their ability to migrate to new technologies and make their IT functions less responsive to market change. That means that technical debt and legacy code negatively affect the digital transformation and evolution of your business as well.

Here are some of the best strategies to reduce code debt in your legacy codebase.

#1 Identify technical debt: Deep dive into system architecture

The first step to reducing technical debt is to identify it. But how do you know where to look? A good place to start is to look at your system’s architecture: make a code review.

The architecture of any software system tells a story about its evolution. It reflects the decisions made by developers in the past, and those decisions can have an impact on future development efforts. When you’re assessing your system’s flexible architecture, keep in mind that too much change can be just as problematic as too little change. The trick is finding a balance.

For more in-depth and effective analytics of your codebase/architecture, you may want to get a professional source code assessment service to take a look. ModLogix also offers advanced legacy software audit services that will help you perform a thorough analysis of your codebase.

Once you’ve identified the areas within your architecture that need improvement; you’re ready to take the next action.

#2 Refactoring legacy code to reduce technical debt

A better option for rewriting legacy code is to refactor the existing code so that it solves its original business problem more effectively. This approach reduces technical debt by making the code simpler, more maintainable, and less buggy. The goal of refactoring is to make it more readable, and easy to change and test.

There are several strategies for refactoring legacy code:

  • Separate concerns into small modules.

The idea behind this strategy is that you should always have small modules with a single responsibility. Split modules with more than one responsibility into smaller modules. Each of these smaller modules should have only one responsibility and should be small enough so you can read it in one sitting.

  • Use dependency injection instead of hardcoded dependencies.

Dependency injection is a design pattern where you inject the dependencies into your objects instead of passing them as parameters or setting them in the constructor. Dependency injection allows us to replace any dependency with another object while keeping our code clean and simple at the same time.

#3 Investing in human resource

As a small business, your team, however small, is your biggest asset. Yet technical debt emerges when technology evolves but your team doesn’t evolve with it. It is primordial to help your team move up the ladder by learning new skills and technologies following the rapid advancements in tech. Do this by creating training programs and growth opportunities for your software developers, product designers, and software architects.

How to Reduce Technical Debt in Legacy Platforms: 5 Best Practices

When it comes to legacy code, there is no one-size-fits-all solution. The best way to reduce tech debt there is to understand your system and its codebases from A to Z, and then decide how to handle the situation accordingly.

#1 Track and document technical debt

The first step is to create a technical backlog of features, fixes, and bugs that need attention – and then develop a workflow. You can use tools like Confluence, JIRA, or Trello – to develop your technical stories on the backlog. This will help you track what needs fixing and when – by creating project milestones with due dates attached to them. You can then add specific issues related to each milestone so everyone knows what needs fixing in which order. Keeping track of a technical backlog should become a regular part of your schedule as a team.

  • Look at your project backlog and identify all the technical debts that need fixing.

  • Break down each one of them into smaller tasks based on complexity, the time required, etc.

  • Create a document for each task with details like description, owner, etc., date started, and expected date of completion.

  • Create another document for the whole project detailing all the tasks that need to be done with due dates etc., so that it can be used as a reference point for everyone involved in fixing these issues.

#2 Get your test coverage up!

Poor testing is what got you here in the first place. The healthiest approach to dealing with legacy code is to increase test coverage as much as possible. Even before you begin refactoring, make sure your developers are writing as many automated tests as they possibly can, but don’t aim for 100% coverage.

Preferably, your developers should go for the bigger functionality and integration tests. Getting a working, automated suite of tests really irons up legacy code, enables stability during code changes, and significantly reduces technical debt.

#3 Manage dependencies wisely

When you’re building a new feature or fixing an existing one, make sure that you’re not going to introduce any new dependencies or break existing ones. 

For example, if you’re building a new feature that depends on a third-party library, consider using an in-house version of that library instead of relying on an external one. If you do need an external dependency, make sure it’s well-documented and easy to maintain.

#4 Avoid changing core logic

By all means, avoid altering the core logic and architecture of your codebase. If there’s no other way but to change a certain piece of logic in your system, try isolating this piece of logic into its module so that other parts of the system can remain unchanged as much as possible during development. This will help avoid breaking existing features or introducing new bugs during future refactoring efforts.

Don’t add more complexity than necessary when refactoring code; keep things simple!

#5 Start small

The best way to get started with reducing technical debt is by fixing existing technical problems one task at a time. Don’t try to fix everything at once — this will only frustrate you and make it more difficult to see progress. Pick one task that needs fixing and focus on that until it’s done — then pick another backlog item and keep going until you’ve got it all under control.

Another important best practice is to get rid of code that doesn’t work anymore, as long as it doesn’t affect the core logic of your application.

Start Fixing Your Tech Debt With ModLogix

Dedicating the time and human resources to fixing technical debt can be costly, especially for small businesses. Instead of trying to figure it out and do everything yourself, you should turn to ModLogix because of our expertise and already established infrastructure with modernizing legacy code systems.

ModLogix is an experienced legacy modernization company with efficient tools and working mechanisms that guarantee great results. We move legacy software solutions to secure, stable and scalable platforms, saving their business value.

Why choose ModLogix for fixing your legacy codebase?

  • Our expertise: With 8 years of experience modernizing legacy software solutions,  ModLogix has helped hundreds of companies provide future proof for their software infrastructure.

  • Credibility: Companies may make promises with regards to modernizing code, but offer little or no results with actually fixing the code. ModLogix is not only heavily appreciated by its clients, but several accolades also speak to our quality: DesignRush Accredited Agency 2020, Top Rated App Development Companies by SoftwareWorld and Clutch accredited.

Some of our portfolio projects aka case studies

  1. Migration from AngularJS to Angular 11

If your codebase is built on Angular, then we’re happy to reduce some of your technical debt by moving your code to the more robust AngularJS framework, just as we did for one of our clients – a premium provider of IT and financial services in the healthcare industry. Being in this highly competitive industry gave our clients no choice but to update their tech stack.

Their management team decided to partner with us, a legacy software modernization company that has solid expertise in Angular and AngularJS. This migration allowed us to perform tremendous technical debt reductions in their codebase.

Read the full project overview here.

  1. Migration from .NET Framework to .NET Core:

One of our clients, a reputable vendor of innovative digital and financial services for the healthcare sector, worked with us to reduce much of the technical debt in their legacy codebase, by upgrading their tech stack from the .NET Framework 4.7,  to .NET Core 3.2. This was a move from limited functionality, to the latest version of this popular framework. The results in their business have been outstanding.

Learn the project details here.

  1. Migration from ASP.NET to .NET Core

Approved Admissions is a cloud-based eligibility verification platform that monitors and reports changes in Medicare, Medicaid, and HMO payers. We helped them achieve smooth migration from ASP.NET to .NET core, which was essential to reducing much of their technical debt. We were successful at helping them improve performance, reduce cost, and improve horizontal scalability, and internal security.

Tap here to learn more about this project.

Final Thoughts

Software development teams are often under lots of pressure to deliver working products within limited time frames. To make things worse, sometimes system requirements are not documented and communicated. Developers are often pushed to resort to bad coding practices that sum up to create so much technical debt – which could break the entire system over time if not taken care of.

This article details effective strategies for tackling technical debt with a focus on legacy codebases. We’ve also shared some of the best practices necessary to curb technical debt; we hope these points help you a bit. If not, our team is ready to provide a detailed consultation regarding your legacy systems or technical debt. 

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