VB6 to .NET Modernisation
Your VB6 applications still run the business. We'll help you modernise them safely.
Why VB6 Applications Are Still Running Your Operations
Visual Basic 6 applications exist because they work. They were built to solve real business problems, and many have been doing exactly that for over two decades. They hold critical business rules, support daily operations, and process transactions that keep your organisation running.
The decision to modernise isn't about the technology being "old". It's about managing risk. VB6's runtime is no longer supported by Microsoft. The pool of developers who can maintain it shrinks every year. Security vulnerabilities cannot be patched. Integration with modern systems becomes increasingly difficult.
The question isn't whether to modernise, but how to do so without disrupting the operations these systems support.
Why VB6 Becomes a Business Risk
VB6 applications that have served reliably for years are now accumulating risks that threaten business continuity. These risks compound over time and become increasingly expensive to address.
Windows Compatibility Uncertainty
Each Windows update introduces the possibility that your VB6 application will stop working. Microsoft no longer tests VB6 compatibility, and there's no guarantee that future releases will support the runtime at all.
Disappearing Expertise
Developers with VB6 experience are retiring or moving on. Recruiting replacements is difficult and expensive. When your current maintainers leave, finding someone who can safely modify the system becomes a serious challenge.
Fragile Integrations
VB6 relies on COM components, ActiveX controls, and legacy database drivers. These dependencies are increasingly unsupported and difficult to maintain. Every integration point is a potential failure waiting to happen.
Security and Compliance Exposure
The VB6 runtime cannot receive security patches. Vulnerabilities discovered today will never be fixed. For organisations subject to compliance requirements, running unsupported software creates audit and liability concerns.
Inability to Add Features
Modern requirements like web interfaces, mobile access, API integrations, and cloud deployment are extremely difficult or impossible to implement in VB6. The platform constrains your ability to respond to business needs.
Rising Maintenance Costs
As expertise becomes scarcer and workarounds accumulate, the cost of keeping VB6 systems running increases. Each year of delay makes eventual modernisation more expensive and more risky.
Modernisation Is Not Just Code Conversion
The temptation to run VB6 code through a conversion tool and call it "modernisation" is understandable. It sounds quick and low-cost. In practice, this approach consistently fails to deliver maintainable results.
The Problem with Automated Conversion
Automated code converters produce syntactically correct code that preserves the original structure. But that structure was designed for VB6, not for modern .NET development. The result is code that:
- Preserves all the original design limitations and workarounds
- Uses patterns that are unfamiliar to modern .NET developers
- Cannot take advantage of .NET's strengths and capabilities
- Is often harder to maintain than the original VB6
- Still depends on COM interop and legacy components
Similarly, full rewrites are often proposed as the "clean" alternative. But large-scale rewrites have a poor track record. They take longer than expected, cost more than budgeted, and frequently introduce regressions that damage operations.
Effective modernisation requires understanding the business logic embedded in the code, capturing actual system behaviour, and rebuilding thoughtfully in a way that serves your organisation for the next decade. This takes careful planning and staged execution.
Our Staged Approach
We modernise VB6 applications incrementally, validating each change before moving forward. This approach maintains business continuity while progressively reducing risk.
Discovery and Dependency Mapping
We analyse your VB6 codebase comprehensively: forms, modules, classes, third-party controls, COM components, database connections, file operations, and external integrations. We identify what the system does, what it depends on, and where the risks lie.
Behaviour Capture Using Real System Outputs
Before changing anything, we capture how the system actually behaves. We record inputs, outputs, calculations, and state changes across representative business scenarios. This creates a validation baseline that ensures modernised components produce identical results.
Risk-Based Migration Planning
Not all components carry equal risk or value. We prioritise based on business criticality, technical fragility, and dependency complexity. High-risk components may be addressed first to reduce exposure; stable components may be migrated later or wrapped rather than rewritten.
Stabilising the System Before Changes
Before migration begins, we address immediate risks: undocumented dependencies, fragile integrations, and single points of failure. This reduces the chance of problems during modernisation and often delivers immediate operational improvements.
Incremental Replacement of Modules
We replace VB6 components one at a time, validating each against captured behaviour before deployment. The system continues operating throughout. If issues arise, we can roll back individual components without affecting the rest.
Migration to C#/.NET
Replacement components are built in modern C# targeting .NET 6/8 or later. We write clean, well-structured code that follows current .NET conventions and can be maintained by any competent .NET developer. No proprietary frameworks, no unusual patterns.
Parallel Verification for Business Continuity
Critical components run in parallel with their VB6 predecessors during transition. We compare outputs continuously to verify correctness. Cutover happens only when we're confident the modernised component matches or exceeds the original's reliability.
Where Automation Helps
Modern tooling accelerates certain aspects of VB6 modernisation. We use automation where it adds genuine value, while keeping architecture, validation, and delivery decisions firmly human-led.
Code Analysis
Automated scanning identifies dependencies, call graphs, and code patterns faster than manual review. This accelerates discovery without missing hidden connections.
Documentation Generation
Tooling extracts business logic documentation from code, creating a foundation for understanding that human analysts can verify and expand.
Test Generation
Automated test creation from captured behaviour ensures comprehensive coverage. Human testers focus on edge cases and business validation rather than routine checks.
Automation is a tool, not a strategy. The decisions that determine success—what to migrate, how to structure it, what risks to prioritise—require human judgement and accountability.
Business Outcomes from Modernisation
Reduced Operational Risk
Systems running on supported platforms with available expertise. No more holding your breath during Windows updates or scrambling when maintainers leave.
Improved Maintainability
Clean, well-documented code that follows modern conventions. Changes that used to take days can be made in hours. Technical debt decreases instead of accumulating.
Easier Hiring and Onboarding
Modern .NET skills are widely available. New team members can contribute quickly without months of learning legacy patterns and workarounds.
Modern Integration Capability
Connect to APIs, cloud services, and modern databases without fragile workarounds. Enable web interfaces, mobile access, and third-party integrations.
Faster Feature Delivery
Modern tooling, frameworks, and development practices accelerate delivery. Features that were impractical in VB6 become straightforward in .NET.
Security and Compliance
Supported platforms receive security patches. Modern authentication, encryption, and audit capabilities address compliance requirements.
What You Receive from an Engagement
Every engagement delivers concrete, documented outputs that provide value regardless of next steps. You're not dependent on us to act on the findings.
Written Assessment Report
A comprehensive analysis of your VB6 system: what it does, how it's structured, what risks it carries, and what options exist for addressing them. Written in plain language for technical and business stakeholders.
Dependency and Risk Map
Visual and documented mapping of all dependencies: third-party controls, COM components, database connections, file systems, and external integrations. Risk-rated by fragility and business impact.
Phased Migration Roadmap
A practical plan for modernisation broken into stages, with clear milestones and decision points. Includes effort estimates, risk assessments, and recommended sequencing.
Proof-of-Concept Options
Recommendations for initial pilots that demonstrate feasibility and build confidence before full commitment. Typically focused on high-value, lower-risk components.
Maintainable Modern Codebase
For migration engagements: clean C#/.NET code following standard conventions, comprehensive documentation, automated test suites, and deployment configurations. Code your team can own and extend independently.
Common Questions About VB6 Modernisation
How long does VB6 to .NET modernisation typically take?
Timelines depend on system size and complexity. Most organisations see initial modernised components in production within 8-12 weeks. Complete migration of larger systems typically spans 6-18 months, delivered in phases that each provide working functionality.
Can we modernise incrementally while the VB6 system keeps running?
Yes. Our staged approach keeps your existing VB6 application running throughout the process. Components are replaced one at a time, validated against captured behaviour, and deployed only when verified. Your operations continue without interruption.
What happens to our third-party VB6 controls and COM components?
We identify all third-party dependencies during discovery and determine the appropriate approach for each: replacement with modern .NET equivalents, wrapping for continued use, or elimination where functionality is no longer needed. No dependency is left unaddressed.
Will our staff need retraining on the new system?
User interfaces are typically redesigned to be intuitive and consistent with modern applications. We provide knowledge transfer for technical staff and can support end-user training as needed. Most users adapt quickly to improved interfaces.
What if we're not ready for full modernisation yet?
The assessment phase provides value on its own. You receive a written report, dependency map, and roadmap that inform future planning. Many organisations use this to secure budget, build internal consensus, or address immediate risks before committing to full migration.
Do you work with systems that have no documentation?
Yes. Most VB6 systems we encounter have minimal or outdated documentation. Our discovery process extracts understanding directly from the code and captures behaviour from the running system. We create the documentation that should have existed all along.
Request an Initial Assessment
Tell us about your VB6 system and we'll provide a written assessment of your modernisation options. No call required to start—just send us the details and we'll respond with initial findings and recommendations.
No obligation. No sales pitch. A practical written analysis you can use regardless of next steps.