Application Modernization
Move your systems forwardwithout rewriting everything.
Legacy applications represent accumulated business logic — some of it valuable, some of it a liability. We assess which is which before recommending anything, then chart a forward path that moves incrementally without stopping the business.
What we provide
Modern, maintainable platforms without the risk of a big-bang replacement.
- Legacy application technical assessment and debt mapping
- Cloud migration — lift-and-shift, replatform and refactor
- .NET Framework to .NET 8 migration
- Monolith decomposition into independently deployable services
- Database migration and schema modernisation
- Automated test coverage added before any refactoring begins
- Incremental UI modernisation — Blazor and React
- Dependency and third-party library upgrades
Why Theerrv
Honest assessment first
We start by understanding the system you have — its embedded business logic, its technical debt and the actual cost of each. We tell you what to keep and what to replace.
Incremental, not reckless
We use the strangler fig pattern and parallel runs where the risk warrants it. The business keeps running throughout the transition — not paused for an 18-month project.
Azure as the destination
Modernised systems land on Azure with proper CI/CD, observability and infrastructure as code from day one — not retrofitted once the migration is done.
Our approach
Discovery → Architecture → Development → Testing → Deployment → Support
Technical assessment
Codebase review, architecture mapping, dependency audit, test coverage check, and a frank discussion of what modernisation will and will not solve.
Modernisation roadmap
Prioritised plan with phases, risk flags, and a clear definition of done for each milestone. Written and agreed before work begins.
Test baseline
Automated tests added to cover critical paths before any code is changed. Tests are the safety net for the refactoring ahead.
Incremental delivery
Changes delivered in tested increments. Legacy system runs in parallel until confidence is established — not replaced all at once.
Cloud migration
Application rehosted or replatformed to Azure, infrastructure defined in Bicep, CI/CD pipeline in place from the first deployment.
Decommission
Legacy systems retired only once the replacement has been running under load for an agreed period. Data archived to compliance requirements.
Technologies
The stack we use to deliver application modernization — chosen for longevity and maintainability, not trend.
- .NET 8
- ASP.NET Core
- Entity Framework Core
- Blazor
- Azure App Service
- Azure SQL Database
- Bicep
- Azure DevOps
- Docker
Industries & use cases
Financial Services
- .NET Framework banking and accounting applications
- VB6 and classic ASP legacy system replacements
- On-premises SQL Server to Azure SQL migration
Manufacturing and ERP
- Legacy ERP module replacement with modern services
- WebForms and Windows Forms modernisation
- On-premises workload migration to Azure
Healthcare IT
- Ageing clinical system migration with data preservation
- SOAP service to REST API modernisation
- On-premises to cloud with compliance maintained
Professional Services
- Practice management system modernisation
- Access database to SQL Server migration
- Desktop application to web application conversion
Common questions
Should we rewrite or modernise our legacy application?
A full rewrite is almost never the right first answer. Legacy systems contain business logic that is rarely documented anywhere else — and a rewrite discards that knowledge along with the technical debt. We look for the smallest changes that produce the greatest improvements: upgrading the framework, adding a CI/CD pipeline, replacing the riskiest components — before recommending anything broader.
How long does a .NET Framework to .NET 8 migration take?
For a well-structured application without heavy third-party dependencies, a migration can take 4–8 weeks. For a large application with WebForms, COM interop, MSMQ dependencies or a tightly coupled database layer, 3–6 months is realistic. The honest answer depends on what we find in the assessment, which is always the first step.
Can you modernise an application while it is still in production?
Yes — and in most cases this is the only viable approach. We use incremental patterns: the strangler fig for component-level replacement, feature flags for safe deployment, and parallel running for the highest-risk migrations. The business keeps operating throughout.
What happens to our data during the migration?
Data is treated as the most critical asset in any migration. We script and test the migration process against a copy of production data before running it live, validate the output against known figures, and run both systems in parallel until the data reconciles within an agreed tolerance. We do not drop or archive old data until you have confirmed the new system is correct.
Related services
Start here
Tell us what theoperation is costing you.
A first conversation is a conversation, not a pitch. Describe how the work runs today and we will tell you plainly whether software is the right answer — and what it would take.
Or reach us directly at info@theerrv.com