Why I Still Believe in the Web Forms to MVC Rewrite: A Case for Transitional Architecture

Modernisation projects are often framed in extremes: you either rewrite everything from scratch or do nothing at all. But real-world projects rarely afford that luxury. At Activus, I was tasked with moving a legacy Windows Forms application to the web and we didn’t do it by burning everything down. We did it by rewriting, piece by piece, with ASP.NET MVC and Razor at the heart of our approach. And I still stand by that decision.

Transitional architecture gets a bad reputation. People worry it leads to Frankenstein systems, half modern and half legacy. But in my experience, it’s often the only path that balances technical risk with business continuity.

At Activus, the original system was built in VB6 and tied deeply into a monolithic desktop UI. The feature set was vast, and a complete greenfield rewrite would’ve taken years - time the business didn’t have. So instead, we introduced MVC as a wrapper, allowing us to replace sections of the old app incrementally.

This approach had multiple benefits:

• Continuity: We could deliver value to the business while the rewrite was in progress. There was no need for a multi-year development freeze.

• Learning curve: The team could adopt new web technologies gradually, rather than being overwhelmed by a complete paradigm shift.

• Refactoring opportunities: Each new module was an opportunity to rethink, improve, and decouple logic that had been buried in the legacy codebase.

Some might argue we should’ve gone all-in with a single-page app or jumped straight to microservices. But that wasn’t the right fit for the team or the problem. What we needed was a solid, testable, maintainable structure that could live alongside the old system and that’s what MVC gave us.

We used Razor views to keep server-side rendering fast and simple, jQuery for front-end interactivity, and Bootstrap to bring some consistency to the UI. It wasn’t flashy, but it worked. And critically, it allowed the team to build confidence and experience with modern web patterns without the pressure of rewriting the universe.

Looking back, that transitional architecture taught me a valuable lesson: you don’t need to modernise everything at once. Sometimes, the best architecture is the one that meets you where you are and takes you where you need to go, one step at a time.

That mindset has served me well in every modernisation effort since.