Legacy Code Conversion Services
Modernising legacy systems is essential for performance, security and long-term viability. Our legacy code conversion services help you transform outdated software into maintainable, scalable and future-ready applications, ensuring your business remains competitive and adaptable.
What is legacy code conversion?
Legacy code conversion is the process of modernising outdated software systems, so they align with current technologies, security standards and business requirements. Instead of replacing systems entirely, legacy conversion focuses on refactoring, restructuring or rebuilding core components to improve performance, scalability and maintainability.
This approach protects your existing investment while ensuring your software remains competitive, secure and adaptable for future growth. If the original developer has vanished or the system is barely holding together, we also take over and rescue legacy software projects.
Signs it is time to convert, not just patch
- The original developer, or the company that built it, is no longer around to support it.
- The language or framework it runs on is no longer maintained (no security patches, a shrinking pool of developers who can work in it, or the vendor has announced end of life).
- Every change takes longer than it should, because the codebase has become too fragile to touch with confidence.
- The system cannot be hosted in the cloud, integrated with newer tools, or accessed from a phone or tablet, because the underlying technology cannot support it.
- You are paying more each year to keep an old system alive than it would cost to modernise it properly.
If two or more of these sound familiar, a conversion is worth scoping. If none of them apply and the system is only missing a few features, a smaller enhancement project is usually the better use of budget.
Not sure if your situation is a conversion project or something more urgent, like a system that is actively breaking with nobody left to call? See our guide on when to convert versus when to hand a system over completely.
Reasons to convert older code
Technologies we convert to and from
We are not tied to one language or framework, so we can plan a conversion around what you already have rather than forcing a rebuild you do not need. We regularly work in:
- Backend: C#, .NET, Python, PHP
- Web front-end: React, JavaScript, WordPress
- Mobile: React Native, .NET MAUI, Xamarin (iOS and Android)
- Databases: Microsoft SQL Server (MS SQL), MySQL
- Integration and AI: REST APIs, SaaS platforms, and AI features (including GPT/RAG) added into your existing system rather than a rebuild
Running something not on this list? Tell us. Chances are we have worked with it, or something close enough that the conversion path is well understood.
Understanding legacy code conversion
Legacy code conversion is the process of analysing, refactoring and rewriting outdated software systems to align with current technology standards. Many businesses still rely on ageing codebases that are hard to maintain, lack integration capability and struggle to support modern workflows.
This process involves evaluating the existing architecture, identifying components that require modernisation, and re-implementing functionality using up-to-date frameworks, languages and design patterns. A successful conversion reduces technical risk, enables smoother future development and positions your software for long-term stability and scalability.
What factors contribute to code being labelled as legacy?
How we approach a legacy code conversion project
1. Code and data audit
We review the existing codebase, database structure, and any documentation that exists (often there is little to none, which is normal, not a blocker). We identify what is safe to carry across as is, what needs rework, and where the real risk sits.
2. Conversion plan
You get a written plan covering scope, sequencing, and a realistic timeline, plus a clear view of what changes for your team and your users and what does not.
3. Phased conversion
We convert in stages rather than one large cutover wherever the system allows it, so the business keeps running on something stable throughout, and we can validate each stage before moving to the next.
4. Data migration and testing
Every record is migrated and verified, not just moved. We test against real data volumes, not a sample, before anything goes live.
5. Handover and support
You get a system your team can maintain, documentation that did not exist before, and ongoing support if you want it. No licence fees, no vendor lock-in, full IP transfer to your business.
Case study: Rebuilding Ecostat with new technology
Ecostat, Netgen's own environmental monitoring platform, is a good example of what a proper legacy conversion involves, because the constraints were real and the stakes were high: hundreds of millions of environmental monitoring records collected over 15 years, from remote weather and monitoring stations across South Africa, could not be lost or corrupted during the move.
The original system was built in 2008 on VB.NET, a solid choice at the time. By 2022, it was starting to struggle under newer demands: cloud access, mobile monitoring, and integration with modern tooling. In November 2022, Netgen began converting the platform to C# and .NET Core, rebuilding the database backend and moving it onto modern cloud infrastructure.
The full data history, hundreds of millions of records, was migrated without loss. The rebuilt system went live in Q2 2023 with added mobile access and white-label functionality for distributors, none of which the original VB.NET system could reasonably support.
Read the full case study: Rebuilding Ecostat with new technology
Common questions about legacy code conversion
How long does a legacy code conversion take?
It depends on the size of the system and how much of it can be converted in phases rather than all at once. A focused conversion of a single core system typically runs a few months; a full platform rebuild with a large data migration, like the Ecostat example above, can take longer. You get a specific timeline after the code and data audit, not before.
Will you convert my existing code, or rebuild the whole thing from scratch?
That depends on what the audit finds. Where the underlying logic is sound, we convert it directly onto the new stack, which is faster and lower risk. Where the architecture itself is the problem, we will tell you honestly and recommend a rebuild instead. We do not default to a rewrite just because it is more billable.
Is my data safe during the conversion?
Yes. Every record is migrated and verified against the source system, not just copied across. On the Ecostat project, we migrated hundreds of millions of records with no data loss. We test against real data volumes before anything goes live, not a small sample.
Do you convert code you did not originally write?
Yes. Most legacy conversion projects involve code Netgen did not build. The audit stage exists precisely to understand someone else's codebase before we commit to a plan and a timeline.
How much does legacy code conversion cost?
It depends entirely on the size and condition of the existing system, so we do not quote a figure without seeing the codebase first. Get a free quote and we will scope it properly after a short code and data review.
If you have lost the source code entirely, or the developer who built the system is gone, see our legacy software rescue and takeover service instead.
Netgen – experts in legacy code conversion
Let’s bring your software and processes into the here and now.