VB6 to .NET

We can upgrade your VB6 code


Visual basic 6 to .NET migration

We have upgraded Visual Basic 6 code bases to .NET using C# and VB.NET.

Your Visual Basic 6 desktop application can be migrated to a .NET web or desktop application. It is possible to use most of the logic of the code within the new application.

A new application is created with .NET, with a new data access technology such as Entity Framework or ADO.NET. The UI elements are created in .NET as per the existing app or as per a re-design. 

Any existing business logic can then be ported with tests. Many of the VB6 and VB.NET language constructs are the same so migrating to VB.NET first can help. Development can then continue with VB.NET for further development or converted to C# to take advantage of the wider range of support and libraries for the language.

Third-party controls such as Syncfusion or DevExpress can be used to replace the existing VB6 controls.

JavaScript or TypeScript can be used to replicate the event-driven code for the UI.

The existing functionality can be recreated using the logic of the existing code.

The benefits of modernizing mean that new features can be added to the upgraded app. New libraries can be integrated. The app can be hosted on the cloud and take advantage of integrations with 3rd party services.

Moving to the web also means that updates can be performed without distributing new installers.

Get in touch if you have a VB6 code you would like to modernize as a desktop or web application.

We have worked on multiple projects with tens of thousands of lines of code. These projects have been successfully migrated to a new platform allowing the project to move forward.

Our Process

  • A call or email to discuss your VB6 project
  • Send a copy of the source code so we can have a look and get it running in a local environment
  • Create a project plan for migrating the code. Highlight the critical functionality of the software.
  • Depending on the nature of the app will depend on how the code is ported. If it is a business/data-driven app then the functionality can be rewritten in C#. 
  • If the app is more complex care will be taken to replicate the same functionality in C#.


If the app runs on an MS Access database it is a good idea to upsize it to something more suitable such as a SQL Server database.

Data Access

In VB6 apps with lots of embedded SQL queries, it is usually possible to migrate the queries without modifying them.

New functionality can use an ORM (object-relational mapper) such as Entity Framework to speed up data access.

Existing queries can be run as raw SQL in the ORM or converted to C# LINQ statements. If using SQL Server or MySQL database they can also be created as stored procedures. It is a matter of preference and may depend on the future plans for the app.

Legal bundle software VB6 upgrade

One VB6 upgrade project we completed was for court bundling software. This was many lines of VB6 code, a forms interface, and integration of third-party libraries like the BCL PDF library.

Details about the process and code for this project can be found on the case study page for the project.


Black Cat Computers Ltd

UK software dev


128 City Road, London, England, EC1V 2NX