Recover
Inventory projects, modules, forms, classes, data access, Windows API calls, controls, libraries and external processes.
VB6 application migration & modernisation
Modernise a critical VB6 application without losing the rules that keep your business running.
Recover the application’s real behaviour, expose fragile dependencies and create a controlled route from Visual Basic 6 to modern, supportable .NET software.
The problem
The application may be old. The business knowledge inside it is not.
Long-lived VB6 systems often support specialist workflows that newer applications do not reproduce easily. The source may contain years of decisions, exceptions and integrations that were never documented anywhere else.
A successful migration therefore begins with evidence. The job is not simply to translate syntax—it is to identify valuable behaviour, operational constraints and technical dependencies, then preserve what matters while removing what makes the system expensive or unsafe.
Unsupported Visual Basic 6 development tooling
COM, ActiveX, OCX and third-party control dependencies
32-bit components blocking platform upgrades
Undocumented business rules and calculations
DAO, ADO, RDO or embedded SQL data access
Fragile installers and manual deployment steps
No reliable automated regression tests
Compiled applications with incomplete source code
The approach
Understand behaviour before changing technology
Migration tooling can assist with parts of the work, but it cannot decide which behaviour is essential, which dependencies are replaceable or how the new system should operate.
Prioritise
Separate valuable business capability from obsolete interface choices, duplicated code and accidental technical constraints.
Modernise safely
Move bounded capabilities to current .NET architecture with reconciliation, regression testing and a controlled transition.
Migration route
Assess. Baseline. Replace. Prove.
- 01
Assess
Map source availability, architecture, dependencies, data, deployment and critical workflows.
- 02
Baseline
Capture current outputs and behaviour so the replacement has evidence-based acceptance criteria.
- 03
Replace
Rebuild agreed capabilities in C# and modern .NET using an appropriate web, service or desktop architecture.
- 04
Prove
Reconcile data and outputs, test operational journeys and support a controlled cutover or parallel run.
Modernisation options
Choose a route that fits the application and the organisation
Reduce the immediate risk
Document the application, repair critical compatibility problems and establish a supportable baseline while replacement is planned.
Replace capabilities in stages
Move suitable data access, integrations or business services behind controlled interfaces while the existing client remains operational.
Build a modern .NET application
Reimplement the required workflows in C# and current .NET without carrying every historical limitation into the new system.
Assessment deliverables
A decision-ready migration route
The initial engagement defines what exists, what matters and what a responsible modernisation programme would involve.
- Source-code and application inventory
- COM, ActiveX, OCX and third-party dependency map
- Database, file and external-integration assessment
- Critical workflow and business-rule findings
- Compatibility, security and operational risks
- Recommended target architecture
- Phased roadmap, decision points and indicative scope
Common questions
What a VB6 migration really involves
Can VB6 be converted directly to .NET?
Some code and concepts may be reusable, but runtime, user-interface, data-access and architectural differences mean dependable modernisation requires engineering—not a blind conversion.
Does it require a complete rewrite?
Not always. Where useful seams exist, data access, integrations or workflows can be replaced in stages while the existing application remains available.
What usually creates the most risk?
Undocumented behaviour, third-party controls, COM dependencies, Windows API calls, deployment routines and weak regression evidence are frequent sources of uncertainty.
Good fit
This service is designed for
- Business-critical VB6 desktop applications
- Systems blocking Windows, Office or infrastructure upgrades
- Applications with valuable but undocumented behaviour
- Teams moving towards C# and modern .NET
- Organisations needing an evidence-based migration estimate
Important constraints
What can affect the scope
- Source-code completeness and build reproducibility
- Application size and number of related projects
- Third-party components and licence availability
- Database and external-system complexity
- The evidence available for behavioural testing
Commercial starting point
Assessment from £3,500 + VAT
A fixed-scope assessment covers one defined application or closely related application set and ends with a written modernisation recommendation. Implementation is scoped separately once the evidence is available.
Request an assessment
Still relying on a critical VB6 application?