Case Study - Migrating a Legacy .NET WCF App in 12 Minutes with Priset

For decades, legacy modernization has been one of the most dreaded tasks in software engineering. It's a high-risk, low-reward process that consumes months of developer time, costs hundreds of thousands of dollars, and often ends in failure.

We believe that era is over.

To prove it, we put Priset to the ultimate test: migrating a real-world, multi-project legacy Windows Communication Foundation (WCF) service to a modern .NET 9 architecture. We didn't use a canned demo or a simplified example. We did it live, and we recorded the entire process.

The result: A successful migration and a running application in 12 minutes, for a total cost of $4.07.

Here's the full timelapse video.

The Challenge: The Legacy Nightmare

The project was a typical example of enterprise technical debt: a WCF service split across three projects, filled with outdated patterns, complex dependencies, and logic that was difficult to untangle. A manual migration would be a multi-week project for a senior .NET developer, involving painstaking analysis, rewriting, and extensive testing.

The Process: A Conversation with an AI Partner

Our goal was to see if our "Developer" model, powered by Google's state-of-the-art Gemini 3 Flash, could handle a task of this complexity. The process unfolded in two key phases inside Visual Studio.

Phase 1: Migration to Successful Build (9 Minutes)

With the legacy solution open, we gave Priset a single, high-level prompt to begin the migration. From there, it worked autonomously:

1. Architectural Scaffolding: Priset created three new .NET 9 projects, mirroring the original structure but using modern templates (e.g., Web API for the service).
2. Code Translation: It systematically read the old C# code, translating WCF-specific contracts ([ServiceContract], [OperationContract]) into modern API controllers and endpoints.
3. Dependency Resolution: It identified and replaced outdated libraries, intelligently refactoring the code to work with their modern equivalents.

After just 9 minutes of autonomous work, Priset achieved a successful build. The core logic was migrated.

Phase 2: Real-Time Runtime Debugging (3 Minutes)

As any experienced developer knows, a successful build is only half the battle. When we ran the new service, the Swagger UI failed to load - a common but often tricky runtime error.

This is where the difference between a simple code generator and a true engineering partner becomes clear.

• Attempt 1 (Vague Prompt): We first told Priset, "It does not show the swagger page when i run it." The AI made an intelligent guess and refactored the launchSettings.json file, but the issue persisted.
• Attempt 2 (Specific Error): We then copied the detailed error message from the browser's window and fed it to Priset. Instantly, it recognized the root cause - missing middleware configuration. It generated the precise fix, applied it, and on the next run, the Swagger interface loaded perfectly.

This two-step debugging process is a perfect example of human-AI collaboration. The AI's ability to reason, attempt a fix, and then course-correct based on specific feedback is what makes it a 100x tool.

Why Other AI Tools Fail at This

We believe in testing against the best. Before this, we attempted the same migration using the most popular vibe coding tool. While it's a powerful tool for line-by-line coding, it was unable to handle the architectural complexity of this multi-project migration and failed to produce a buildable solution.

The key differentiator is Priset's ability to understand the entire context of a solution, orchestrate changes across multiple projects simultaneously, and maintain a stateful understanding of the overall goal. It's not just completing code; it's executing an engineering plan.

The Bottom Line: The ROI is Undeniable

Let's break down the numbers:

• Manual Effort: 2-3 weeks of a senior developer's time (~$5,000 - $7,500 USD).
• Priset Effort: 12 minutes of AI work.
• Total Cost: 83 AI credits, equivalent to $4.07 USD.

This isn't just an incremental improvement. This is a fundamental disruption to the economics of software maintenance and innovation. Companies are no longer held hostage by their technical debt.

The 100x developer is here, and they are ready to modernize your enterprise.

Ready to tackle your own legacy nightmare? Start your free Priset trial.