What We Learned Modernizing a Complex VB6 System with Gen AI for a Fuel Distribution Software Company

Legacy VB6 systems are notoriously painful.

Our recent work with a UK-based fuel distribution software company showed us exactly why.

They relied on a fat-client VB6 transaction system that had served them for 30+ years, supporting 500–600 users across industries. But as business grew, the system became a bottleneck, struggling to scale and maintain performance without skyrocketing costs.

The company needed a modernization plan that wouldn’t break the business or blow the budget.

Here’s what we learned from this project:

1. Intelligent refactoring beats full rewrites, every time

A multi-million-dollar rewrite wasn’t feasible. Instead, we applied Gen AI to intelligently refactor core business logic, automate 50–70% of the code transformation, and preserve key functions. This balances speed, cost, and accuracy.

2. Automated testing is essential in complex, configurable apps

Manual testing wasn’t an option for the highly configurable system. We generated AI-powered functional and regression tests to reduce manual effort by 80%, enabling continuous testing and faster go-to-market.

3. Incremental deployment protects business continuity

A phased rollout with hybrid deployment allowed select users to transition early, gathering real-time feedback and minimizing disruption.

4. Cloud-ready architecture means scalability without surprises

The migration wasn’t just a code upgrade. It was building a platform for future growth with cloud scalability baked in, cutting costs by 60% compared to traditional methods.

This wasn’t a theoretical experiment. It was a practical, budget-conscious modernization with measurable impact, proving that legacy VB6 apps can evolve without massive rewrites or downtime.

👉 Read the full case study to see how AI-powered modernization made the difference.