Integrating new features into legacy system
Extending legacy software is critical because they often sustain business-critical operations within an organization. Rewrites or full migrations are often too risky and expensive. In numerous cases, a focused approach provides a higher return on investment.
The client context
A large financial enterprise operating across Europe, specializing in payment processing and Point of Sale (POS) services, relied on an internal tool to manage software package releases. This tool enforced strict access control and electronic signing to ensure the integrity of all deliveries.
The challenge
The internal web application had been developed by an external vendor, but the source code was never delivered. To modify the system, the client was forced to a follow a decompilation process. New functionalities were needed to support evolving software package requirements.
Our mission and approach
We were tasked with integrating new features into this legacy system while strictly preserving its existing behavior. No regressions were acceptable. This business-critical tool ensured the integrity of all delivered packages.
To achieve this, we implemented a controlled, iterative strategy:
- Robust test coverage: developed a comprehensive test suite targeting core functionalities at risk of being impacted by changes.
- Enhanced observability: implemented a structured logging strategy to improve monitoring and debugging.
- Quality assurance: integrated static analysis tools to elevate code quality and detect hidden issues.
- Stakeholder alignment: collaborated with technical and business teams to reconcile documentation with actual implementation and usage.
Key results
Beyond delivering new features while ensuring full backward compatibility, we:
Uncovered and fixed latent bugs in the application. Reduced operational overhead and improved response times.
Why this project matters
This case exemplifies our philosophy: controlled, iterative enhancement of legacy systems. Instead of risky rewrites or large-scale refactoring, we create value through small, strategic steps that minimize risk.