All you need to know about software reengineering in 2025

Imagine you’re handed a big, messy codebase that’s 10 years old. It barely works. Every time someone touches it, something else breaks. And nobody really understands how it was built in the first place. So, what do we do to make everything work properly? We can use reengineering! This is how MWDN software architects explained to us the key point of software reengineering. 

 

At its core, software reengineering is about taking an old system, figuring out how it works, cleaning it up, and making it better, without rewriting it from scratch. You don’t just toss the code and start fresh; instead, you analyze, refactor, and reshape what’s already there to make it more maintainable, scalable, and modern.

Content: 

• Further drivers and benefits of software reengineering
• What does a software reengineering process look like?
• Reengineering methodologies
• Common software reengineering techniques
• Challenges of software reengineering and how staff augmentation can help
• What kind of specialists do you need for software reengineering?
• Summing up

When companies invest in software reengineering, they often see substantial cost savings and improved agility.

Generally, companies report reductions in maintenance costs over five years compared to building entirely new software. At the same time, development teams become more productive thanks to cleaner codebases, modern tooling, and better architecture.

But when should you consider reengineering outdated systems? Typically, after about 10 to 15 years, when business needs have evolved beyond what the legacy system can support, leading to slow updates, frequent bugs, and rising upkeep costs.

Overall, if your software still runs but feels slow and expensive to maintain, reengineering is a safer and more cost-effective way to improve it without starting from scratch.

Further drivers and benefits of software reengineering

Why exactly do companies choose reengineering instead of completely starting over? Here are some of the common reasons:

1. Extended software lifespan. Legacy application reengineering can help you keep your existing systems alive and useful, even as technology evolves. Instead of scrapping an old but functional system, you can modernize it to meet current business needs.

2. Work on improving software maintainability. Over time, software often becomes messy and hard to manage due to quick fixes and accumulated technical debt. Reengineering helps clean up the codebase and make it more modular, readable, and easier to work with.

3. Enhanced performance and efficiency. Old systems may lag due to outdated logic, inefficient database queries, or bloated processes. System revitalization helps identify and optimize these bottlenecks and make load times faster and operations smoother.

4. Increased flexibility. Software architecture redesign makes it easier to integrate with modern platforms, support new features, and comply with updated regulations. A reengineered system is more flexible and better equipped to handle change, whether it’s adding new APIs or expanding to new markets.

5. Cost efficiency. Compared to full rewrites, reengineering is a far more cost-effective modernization strategy. It reduces the need for long, expensive redevelopment projects and helps avoid business disruptions.

6. Increased security. Many legacy systems rely on outdated technologies that are vulnerable to attacks. Reengineering offers a chance to patch known security flaws, replace deprecated libraries, and introduce modern security protocols.

7. Better user experience. Reengineering can vastly improve system responsiveness, stability, and usability. This leads to smoother workflows, fewer crashes, and faster interactions for users.

8. Addressing outdated technology stacks. Many companies run on legacy code that relies on frameworks or languages no longer supported. Reengineering helps move the system to a more modern and supportable tech stack.

9. Solving scalability issues. Older systems often weren’t built to handle the scale businesses face today. As user bases grow, performance can suffer. Reengineering can help you redesign critical components to ensure the software performs reliably under heavier loads and set the foundation for future growth.

What does a software reengineering process look like?

The reengineering process is a structured series of steps that guide the examination, cleanup, improvement, and modernization of an existing software system. Here’s how it goes:

– Initial assessment. The development team evaluates the current system’s limitations, identifies technical debt, and pinpoints what needs to be improved. Once the problems are mapped out, the next step is…

– Reverse engineering. Here, the team analyzes the existing application to recover design elements, business logic, and architecture that might not be well documented. It’s about figuring out how the system really works, especially if it’s old or poorly documented. With a clearer understanding of the current setup, the team then moves on to…

III. Restructuring. This phase focuses on improving the internal code structure without changing what the system does. It includes cleaning up duplicated logic, improving readability, removing outdated components, and simplifying complex code. All to make the system more maintainable and less prone to bugs. The following phase is…

– Forward engineering, where new design principles and legacy system modernization are applied. This is the part where software enhancement is introduced: integrating new APIs, introducing a modern architecture, etc. Next comes…

– Data reengineering, which addresses the underlying data structures. Here, the team works to clean, correct, and reorganize the database, eliminating redundant fields, fixing inconsistencies, or even migrating to more modern storage solutions.

Reengineering methodologies

While the process gives us a roadmap, methodologies define how we actually carry out each stage. These are the strategies, tools, and best practices used throughout application modernization.

Strangler Fig pattern. One widely used methodology is the Strangler Fig pattern, a way to incrementally replace parts of an enterprise architecture. Just like the tree it’s named after, this pattern slowly wraps new functionality around the old one until the original is fully replaced. With this method, the teams can deploy in phases, which reduces risks and costs.

Model-based analysis. During reverse engineering, a common methodology involves using model-based analysis, such as generating UML diagrams or architectural maps, to visualize how the legacy system is structured. This can uncover hidden dependencies or forgotten logic that’s critical to preserve.

Refactoring patterns are often used in the restructuring phase. These include time-tested techniques such as extracting methods, renaming variables for clarity, and breaking monolithic functions into modular components.

In forward engineering, many teams follow clean architecture or domain-driven design principles. These methodologies help reengineer systems in a way that separates core logic from frameworks and UI layers, which makes future changes far easier and less risky.

When it comes to data reengineering services, data migration and normalization tools are often used. They help restructure old databases, remove duplicates, and enforce consistent formats.

Common software reengineering techniques

Methodologies are not the whole picture. When you decide to modernize and improve your software systems, you will apply a mix of reengineering techniques below.

Code refactoring

Refactoring is the process of restructuring existing code without changing its external behavior. The goal is to make the code cleaner, more readable, and easier to maintain. This might involve breaking large functions into smaller ones, renaming variables for clarity, eliminating duplicate code, or simplifying complex logic. Refactoring helps with technical debt reduction and can significantly cut debugging and onboarding time for new developers.

Architecture redesign

Many legacy systems are built on monolithic architecture, where all components are tightly coupled in a single codebase. As business requirements evolve and systems grow in complexity, this structure becomes a bottleneck. Here, you can try out a monolith to microservices transformation. 

This technique breaks down the large, interdependent codebase into a microservices architecture, where each service is responsible for a specific function and communicates with others through well-defined APIs.

This transformation can help you develop, test, and deploy services independently. It also reduces the risk of large-scale failures, since issues in one service don’t bring down the entire system.

Database optimization

Database optimization focuses on improving query performance, it eliminates redundant data and restructures schemas to match modern application needs. It involves adding indexes, normalizing or denormalizing tables, or even migrating to newer, more efficient database engines.

Documentation improvement

Legacy systems often suffer from poor or outdated documentation, which makes onboarding new developers harder and increases the risk of missteps. A focused reengineering effort will include updating or writing new documentation from API references to architectural diagrams.

Automated testing integration

Introducing automated testing, such as unit tests, integration tests, or end-to-end tests is a major step in stabilizing and modernizing a codebase. Automated tests help catch regressions, speed up release cycles, and give developers confidence that changes won’t break existing functionality.

DevSecOps implementation

The integration of security into the DevOps cycle ensures that security is not an afterthought. This includes automated vulnerability scans, dependency checks, and infrastructure-as-code security.

Challenges of software reengineering and how staff augmentation can help

While software reengineering as a part of your IT strategy offers huge benefits, like improved performance, maintainability, and adaptability, it can also bring some challenges. Here are some of the hurdles you should expect and ways how staff augmentation can help you deal with them.

Complexity of legacy systems

Over the years, quick fixes, patches, and ad hoc solutions pile up, resulting in tightly coupled, fragile codebases. Even a small change in one area can unexpectedly break something in another.

How does staff augmentation help? You can hire experienced legacy specialists or system analysts through staff augmentation. They will help you with complex code and map dependencies, while their expertise will reduce the risk of costly missteps.

Lack of documentation

Many legacy systems come with little to no documentation. Original developers may have left the company, and tribal knowledge may be long gone. This makes it difficult to understand how the system works, what each module does, and what consequences a change might have.

Staff augmentation to the rescue! You can outstaff technical writers, business analysts, or system reverse engineers to help rebuild the missing documentation while the reengineering project progresses.

Risk of breaking existing functionality

One of the biggest fears during reengineering is introducing regressions, breaking functionality that previously worked.

By hiring test automation engineers or QA professionals with a reliable staff augmentation partner, you can quickly set up regression testing systems that catch bugs early.

High cost and time investment

Digital transformation via reengineering isn’t a quick fix: It takes time to understand, plan, and gradually transform the system, especially when balancing ongoing feature development. This can put a strain on existing teams and delay roadmaps.

Instead of overloading your in-house developers or hiring permanent staff, augmenting your team with temporary, specialized developers for system performance optimization or microservices migration helps you scale resources flexibly, meet deadlines, and reduce burnout.

What kind of specialists do you need for software reengineering?

So, you decided to modernize your software in-house and now need some extra help? Here are the specialists you will need for reengineering: 

1. Software Architect. They will design the new structure of the system. Software architects make key decisions about reengineering strategies and work on system scalability and maintainability.
2. Senior Software Engineer. Software engineers are the backbone of every development or reengineering project. They will lead the hands-on rewriting, refactoring, and restructuring of legacy code, as they are deeply familiar with both the existing system and the modern approaches being applied.
3. DevOps Engineer. They will set up CI/CD pipelines to support a gradual migration and testing process. They help with smooth deployment during reengineering, manage environment transitions, and rollback strategies.
4. Database Engineer / Data Migration Specialist. These experts will reengineer the database layer: clean data, redesign schemas, and improve performance. They handle data migration, redundancy removal, and integration with new systems.

How much would these specialists cost you?

According to recent data in open sources with average salaries of tech specialists in Israel, here are the annual salaries of talent you will need for software reengineering:

• Software Architect: $100K – $120K
• Senior Software Engineer: $115K – $130K
• DevOps Engineer: $105K – 157K
• Database Engineer:  $75K – $85K

But with MWDN, you can drastically cut your costs and hire much more affordable specialists from Eastern Europe and other regions of the world:

• MWDN Software Architect: $80K – $100K
• MWDN Senior Software Engineer: $75K – $90K
• MWDN DevOps Engineer: $75K – $80K
• MWDN Database Engineer: $60K – $65K

(These numbers can change depending on your requirements and other factors.)

Summing up

Software reengineering can help you move forward. Moreover, sometimes it is unavoidable. However, it will help only if done right. The challenges are real, but so is the help you can get from MWDN, your strategic partner in finding and hiring top specialists to help you with any kind of digital transformation. Want to reinforce your team with top performers? Let’s connect!