Your Legacy .NET System
Is Holding You Back

We migrate mission-critical .NET Framework applications to modern .NET 8/9 — preserving your business logic, eliminating technical debt, and giving your team the confidence to ship again.

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Enterprise .NET Services

End-to-end modernization for mission-critical applications

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.NET Framework Migration

Strategic migration from .NET Framework to .NET 8/9. We understand why the original code was written the way it was — and we modernize it without breaking what works.

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Cloud-Native Architecture

Replatform to Azure, AWS, or on-premise Kubernetes. Microservices architecture, containerization, and CI/CD pipelines designed for your scale.

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Performance Optimization

Database query optimization, caching strategies, and async programming patterns that reduce latency on existing codebases — without a full rewrite.

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Legacy System Rescue

Critical systems with no documentation, no tests, and no one who understands them anymore? That's exactly where we start. We add coverage, reduce risk, then modernize.

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Why Renfield Software?

We specialize in one thing: legacy .NET systems that engineering teams have stopped wanting to touch

35+

Years of combined .NET expertise across the team

.NET 8/9

Current-generation target for every migration we deliver

Zero-downtime

Migration approach that keeps production running throughout

Test-first

We add coverage before we change anything — no blind refactoring

How We Approach a Migration

No two legacy codebases are the same. Our process reflects that.

1. Architecture Assessment

We spend time understanding your system before proposing anything. What does it actually do? Where are the real risks? What can't break? This shapes everything that follows.

2. Test Coverage First

Before we change a line of production code, we add unit and integration tests to the critical paths. This is non-negotiable — it's how we migrate without introducing regressions.

3. Incremental Migration

We don't rewrite everything at once. We move the system piece by piece using proven patterns like the strangler fig, keeping you operational throughout.

4. Knowledge Transfer

Your team owns the result. We document what changed and why, and we don't leave you dependent on us to understand your own codebase.

Meet SwitchCraft

Our flagship configuration management platform, built from 35 years of enterprise consulting experience. The tool we wished we had on every migration project.

  • Feature flags without code deployments
  • Customer-tier management for SaaS
  • Emergency kill switches for production issues
  • Complete audit trails for compliance
Explore SwitchCraft →
Our Product
[SwitchCraft Dashboard Preview]

Not sure if your system qualifies?

Start with a free architecture review. We'll tell you honestly whether migration makes sense, what it would involve, and what it would cost. No commitment required.

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