Delphi to .NET Modernization and Migration with Codeways Toolkit

Delphi. It was the go-to tool for building fast and reliable desktop apps, especially in finance, healthcare, and manufacturing. Launched in 1995 and based on Object Pascal, Delphi made it easy to build database-driven applications. A lot of those apps are still running today, which says a lot about how solid the tech was.

But times change. While Delphi has evolved, many older apps are starting to show their age. That's why more and more companies are looking to modernize, often by moving to Microsoft .NET

Why .NET? It offers better performance, stronger security, cloud readiness, easier updates, and a bigger talent pool. If you're thinking about migrating (or already knee-deep in it), let's walk through what the process looks like and how to make it a success.

Challenges in Delphi to .NET migration

Moving from Delphi to .NET isn't just a copy-paste job but a big project with some real challenges. Knowing what you're up against will make all the difference when it comes to doing it right.

Technical barriers

• UI/UX modernization. Delphi's old-school VCL was great for building Windows apps, but translating the complex forms to .NET (WinForms, WPF, or even web-based UIs like ASP.NET Core) isn't straightforward. Many UIs look outdated and need a full redesign to meet today's standards. Sometimes people use hybrid solutions (like embedding web UIs into Delphi apps), but often it's better to rebuild the UI entirely in .NET.

• Third-party component replacement. Delphi apps often use third-party tools for things like grids or reporting. Finding .NET versions of the same tools or even anything close can be tough. In some cases, you might have to rebuild features from scratch.

• Unicode and encoding issues. Delphi made a big jump to Unicode in 2009. If your app was built before that, you're probably dealing with ANSI strings. During migration, you'll need to be extra careful with string handling to avoid weird bugs or data corruption.

Operational risks

• High maintenance costs (pre-migration). Maintaining legacy Delphi systems is getting more expensive. Developers are harder to find, hardware is outdated, and fixing bugs or adding features is a slow and painful process.

• Talent scarcity. It's not easy to find developers who know both Delphi and .NET. You need people who understand the old code and rebuild it in the new environment, which makes hiring pricey and slows things down.

Strategic pitfalls

• Underestimating complexity & ROI. Many companies assume the migration will be quick and cheap. Spoiler: it's often not. Without a solid business case and a clear app modernization plan, things can drag on or even fail. We suggest investing at least 40–80 hours upfront just for planning and analysis to really understand what you're getting into.

• Inadequate testing. Skipping or rushing testing is a recipe for trouble. You could end up with missing features, bugs, slow performance, or even data loss. So, it’s best to plan for full testing: unit, integration, performance, security, and user testing.

But not every migration needs the same strategy, and trying to use a quick automated tool on a complex system can backfire. Some apps need a full redesign. It all depends on your app's complexity, budget, goals, and timeline.

The good news is that you can avoid these challenges with careful planning, the right expertise, appropriate tools, and a clear understanding of what you ultimately need.

Read more: 11 Reasons Why Companies Fail at Cloud Migration and How to Succeed

Choosing your path: Delphi to .NET migration strategies

So, you've decided to modernize your Delphi app and move it to .NET, great! Now comes the big question: how do you actually do it? In general, there are two main ways to go:

1. Start from scratch (manual rewrite)

2. Take a hybrid approach (mix of automation and manual work)

Before jumping in, it's super important to take a good look at what you're working with. That means reviewing your existing Delphi code, spotting any third-party tools or database connections, understanding how your business logic works, and figuring out where you want to go, like .NET Framework or .NET Core, WPF or ASP.NET Core, etc. That upfront assessment will help you choose the right path.

Let's break down both strategies.

A. Manual rewriting (starting fresh)

• What it is: You rebuild the entire app from the ground up in .NET. The old Delphi code serves more as a reference than something you copy over. You redesign the architecture, write fresh code, and build a new UI, basically a whole new app with the same (or better!) functionality.

• Pros: 

  • Full control over everything: architecture, code, UI, performance.

  • Great for future-proofing and lets you adopt modern practices like cloud-native, microservices, or DevOps.

  • Ideal if your app has complicated logic or a lot of custom features.

• Cons: 

  • Slower and more expensive.

  • Can be risky if you don't fully understand the original system.

  • Needs solid planning to avoid disruptions and missed features.

• Best for: Big and complex legacy systems that need a full overhaul, or when automation just won't cut it.

B. Hybrid approach (automated conversion + manual adjustments)

• What it is: You use automation tools like CodeWays to handle the simpler parts of the code and manually work on the tricky things, like complex business logic or the UI. Some teams also use a phased approach, migrating one piece at a time and letting old and new parts work together for a while using APIs.

• Pros: 

  • Faster and more cost-effective than a full rewrite.

  • Less disruption, and you can modernize gradually.

  • Lets you keep proven Delphi logic and upgrade the rest.

• Cons:

  • Needs good coordination between the automated and manual parts.

  • Running Delphi and .NET side by side is not always simple.

• Best for: Large apps where downtime isn’t an option, and a full rebuild is too expensive or risky.

Want a quick visual of how they stack up? Here’s a handy comparison table:

The key takeaway is that the "right" strategy emerges from understanding the specific application and business context through a detailed assessment.

Spotlight on tools: CodeWays

If you're leaning toward a hybrid approach for your Delphi to .NET migration, the next step is picking the right tool. One standout option is CodeWays by Ispirer, a smart and flexible tool built to handle tricky application migrations like Delphi to .NET.

So, what makes CodeWays worth a look?

It's built for code conversion

CodeWays focuses on transforming source code, like Delphi, to modern languages such as C# or VB .NET. It's part of Ispirer's broader toolkit, which also handles databases and assessments.

It's not just "copy and paste"

CodeWays uses intelligent automation and analyzes your code deeply, looking at data types, objects, even complex language differences, and makes smart decisions during conversion.

It's super customizable

Need the migration to follow your company's coding standards? No problem. Ispirer can tweak the rules to fit your project, which helps get more done automatically and reduces manual cleanup.

It goes beyond the code

CodeWays can convert your UI (like VCL forms) to .NET (WinForms, WPF, or even web apps), business logic, and database layers. It can even help transform old desktop apps into new web-based systems.

It keeps things clean

The goal is to generate readable and maintainable .NET code that your devs can easily work with, avoiding weird dependencies or messy output. For extra complex projects, Ispirer uses helper frameworks to keep things tidy.

It comes with support

You're not alone. CodeWays works alongside other Ispirer tools, like InsightWays for assessments and SQLWays for database migration. And yes, real experts are available to guide you through setup, issues, and customization.

In short: if you want optimized app conversion backed by real people, CodeWays is a strong option to have on your radar.

Delphi to .Net migration roadmap at a glance

Modernizing legacy Delphi applications isn't something you do overnight. It's a structured process:

• Business analysis: First, it's all about the big picture. What's the return on investment? What are the risks of staying put versus moving forward? What should the future architecture look like? You need to map this out, aligning business objectives with technical goals.
  
  

• Code audit: Before any code moves, a deep dive into your existing application is essential. This audit surfaces deprecated functions, tangled third-party dependencies, and lurking security vulnerabilities. Knowing what you're working with sets the stage for a smoother migration.
  
  

• Tool selection: Not every project calls for the same approach. For some, automation is the clear winner. For others, manual rewriting makes more sense, especially when refactoring or redesigning parts of the app.
  
  

• UI/UX modernization: Delphi UIs weren't exactly designed for modern expectations. This is your chance to revamp the look and feel, implementing responsive design, accessibility standards, and a user experience that works across new browsers and devices.
  
  

• Database & cloud integration: Whether you're using local databases or planning a full cloud migration, CodeWays plays well with tools like SQLWays to transition your data. Migrate to platforms like Azure, AWS, or GCP and maintain consistency and integrity.
  
  

• Testing & validation: Performance profiling, automated testing, and real user feedback will make sure the migrated application works (and works better). Quality assurance is built into every phase.
  
  

See how other companies have already accomplished the same task with a plan, structure, and expert Ispirer guidance.

Delphi to .NET migration in action

Theory and tool comparisons are helpful, but seeing how migration projects play out in the real world provides valuable lessons. Here's one example that showcases what's possible with the right expertise and tools:

A health insurance provider's Delphi migration journey

Our client was a U.S.-based health insurance company that had been delivering care services for over six decades through a vast network of hospitals and institutions.

Challenge:
They needed to modernize a legacy application built in Delphi by migrating it to C# .NET with a Windows Forms UI. The scope was substantial, over 200,000 lines of code, and required precise execution to preserve business logic and functionality.

Solution:
To kick things off, the client requested a Proof-of-Concept (PoC) to validate feasibility. Our technical team took on the challenge and completed the migration of approximately 7,000 lines of code in just two weeks. This was possible thanks to Ispirer's deeply refined Delphi-to-C# .NET conversion capabilities and a mature toolkit that minimized the need for extensive customization.

Outcome:
The PoC resulted in a fully functional solution, and its scope was successfully automated. The client was impressed by both the quality of the work and the short turnaround time, which laid the groundwork for moving forward with confidence on the full-scale migration.

Lesson:
For complex migrations like Delphi to .NET, a well-executed PoC makes all the difference, proving technical capability and showcasing tangible value early on.

Read more: Delphi to C# .NET, United States

Is your legacy Delphi app holding you back?

Delphi apps were once reliable, but today's tech challenges, like security risks, performance issues, and a shrinking developer pool, make sticking with legacy systems risky.

Migrating to Microsoft .NET brings major benefits:

• Scalability: Apps that grow with your business
  
  

• Security: Up-to-date protection and regular updates
  
  

• Cloud-ready: Easy integration with platforms like Azure
  
  

• Larger talent pool: Easier and more affordable hiring
  
  

• Easy integration: Connect with modern APIs and tools
  
  

• Long-term viability: A future-proof platform
  
  

Modernizing isn't just a tech upgrade, though. It's a strategic business move, so you need to be ready to make the switch. Don't know where to start? Contact the CodeWays team at Ispirer for a free assessment and a personalized migration plan to move your Delphi app to a powerful .NET foundation!