The Challenge

Our client, a mid-sized insurance provider, was held back by a heavily outdated legacy system. Their core platform was a tightly coupled monolith built in vanilla Java 8 — with no frameworks, no modularity, and no testing infrastructure.

The deployment process was entirely manual. To run the application, engineers had to SSH into the production environment and execute bash scripts on Oracle WebLogic. What made the deployment longer.

The codebase itself was difficult to work with. Since Java classes were deeply interdependent, writing unit tests was virtually impossible. Even minor changes could cause unexpected side effects in unrelated parts of the system. As a result, development velocity slowed dramatically — new features took 7–12 days to ship.

And there was a hidden cost: the team couldn’t attract new developers. Candidates were discouraged by the outdated code and lack of structure. Juniors had no clear way to grow, and seniors saw technical stagnation.

The Solution

We assigned one of our senior Java engineers to lead a refactoring initiative that wouldn’t disrupt business operations.

Step 1: Introduce Spring Boot Gradually

Rather than rewriting whole the legacy monolith and one step, we moved step by step. We add Spring Boot and developed a static helper that let existing classes invoke Spring Beans, even if they weren't Spring-managed themselves. This allowed us to gradually refactor required classes without touching the other code.

Step 2: Align Refactoring with Business Work

We defined a clear rule: if a developer touched a class for a feature or bug fix, they also had to refactor that class into the new architecture. This added minimal overhead but steadily improved the structure — one business task at a time.

Step 3: DevOps Upgrades

With the legacy monolith now far more maintainable, we implemented DevOps best practices:

• CI/CD pipelines for faster delivery

• Static code quality checks

• Antivirus integration

The Results

After just two months of gradual refactoring, the transformation was clear:

• ~80% of the most-used code had been modernized

• Feature delivery time dropped from 7–12 days to 3–5 days

• The system became more stable and testable

• Developers began writing unit tests for newly refactored modules

• Bug fixes no longer introduced unrelated issues

• Team morale improved, and confidence in the codebase returned

Team Growth

Most notably, the company was finally able to hire two junior developers — something they had struggled with for years. With a cleaner, testable, and structured codebase, new team members could onboard quickly and contribute with confidence.

This brought the system in line with modern development standards — and set the foundation for cloud migration.

Conclusion

This case proves that legacy systems don’t have to be rewritten. With focused, incremental refactoring, even a rigid monolith can be transformed into a maintainable, scalable, and cloud-ready platform — all while business continues as usual.

And the impact isn’t just technical. A clean, modern codebase attracts talent, improves retention, and boosts team confidence.