Cloud Migration

Visual Basic 6, Delphi and FoxPro are among the most common technologies we encounter during migrations. These applications were typically built between 1998 and 2008, run on Windows Server, use proprietary databases and have no API. While they still work reliably to this day, maintenance costs keep rising and developers for these technologies are virtually impossible to find.

A simple lift-and-shift (moving to a cloud server without changing the code) usually isn't enough for these applications. VB6 components depend on COM objects, Delphi applications on specific Windows libraries and FoxPro on local databases. That's why we take a gradual rewrite to .NET Core approach where we rewrite the application into .NET Core and shape it around what the company actually needs today.

We start by mapping existing functionality. We go through the code form by form, document business rules and design the new architecture. We migrate the database to Azure SQL or PostgreSQL with full data validation. You can see what such a project looks like in practice in our Helvetia case study, where we rewrote a Visual Basic application into .NET Core with microservice architecture on Azure.

The biggest concern during migration is service disruption. Your users and customers can't wait while the system is being moved. That's why we use a blue-green deployment strategy that ensures the transition to the new system happens without any downtime.

The principle is straightforward: the old system (blue) runs in production while the new system (green) is prepared in parallel. Once the new version is tested and stable, we gradually switch traffic: first internal users, then a small percentage of customers and finally all traffic. If any issue arises, we switch back to the old system within seconds.

During the transition period, we synchronize data bidirectionally so both systems work with the same up-to-date information. Gradual traffic switching is managed through a load balancer, giving us precise control over what percentage of traffic goes to the new system. The rollback strategy is always prepared and tested in advance.

The entire process requires careful infrastructure coordination, from setting up CI/CD pipelines through monitoring to automated tests that verify functionality after every deployment.

Migration to the cloud is just the beginning. For your application to run reliably, it needs stable operations: monitoring, automatic failover, backups and load-based scaling. We handle all of this as part of our cloud services, more in the cloud and server management guide.

We design infrastructure with high availability in mind. Load balancing distributes traffic across multiple servers, automatic failover ensures that one server going down does not mean your app goes down. At the database layer, we implement replication complemented by regular backups.

Monitoring is built on Prometheus and Grafana with predefined dashboards for key metrics: CPU, memory, latency, error rate. We fix problems before you notice them. We applied a similar approach for international e-commerce Helvetia, where we ensure stable operation across 7 countries with zero critical outages.

We automate deployments via CI/CD pipelines - a push to the repository triggers tests and deploy with no manual steps. Zero-downtime deployment and easy rollback to the previous version are standard.

Migration cost depends on several key factors: the technological complexity of the existing system, data volume and quality, the amount of technical debt in the code, and the number of integrations with surrounding systems. A straightforward migration of a smaller application starts in the tens of thousands of euros, while a complex enterprise project with multiple modules and an extensive database can reach six figures.

However, it's important to look at migration from a return on investment (ROI) perspective. Legacy systems carry hidden costs that grow every year: expensive maintenance by specialists in outdated technologies, downtime caused by unreliable infrastructure, missed opportunities due to the inability to integrate modern tools, and security risks from systems without current patches.

After migrating to Azure, operational costs typically drop by 20–40% thanks to the pay-as-you-go model, auto-scaling and elimination of on-premises hardware. Total cost of ownership (TCO) usually pays for itself within 18–24 months. On top of that, you get a system that is scalable, secure and ready for your company's future growth. During a free initial consultation, we'll prepare a rough cost estimate and TCO analysis so you have a clear picture before making a decision. After migration, you can further automate processes via AI agents.