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Modernize legacy .NET, React, and Angular systems without disrupting business operations. TwinCore is a legacy software modernization company that helps enterprises upgrade outdated applications, architectures, and infrastructure with full data preservation and minimal downtime.
TwinCore has elevated the client's customers to the next level of supply chain management. The team is highly cost-efficient from a project management standpoint, and internal stakeholders are particularly impressed with the service provider's team dynamic.
If three or more of these match your system, modernization is no longer optional maintenance. It is a budget decision. Across $1B+ companies, CIOs report that 10–20% of the technology budget for new products is already diverted to servicing technical debt (McKinsey, 2020).
Run your system against these eight signals:
Built on .NET Framework, ASP.NET MVC 5, or Web Forms, stacks Microsoft never moved to modern .NET (Microsoft lifecycle).
Frontend on AngularJS (end-of-life since 2021) or an out-of-support Angular version; Angular supports each major for just 18 months (AngularJS EOL, Angular releases).
New features take weeks to ship because a small change ripples through code no one wants to touch.
Infrastructure costs keep climbing while traffic stays flat.
Security patches are no longer published for core dependencies.
The team routes around critical modules instead of editing them, because the blast radius is unknown.
Documentation is incomplete, outdated, or gone with the people who wrote it.
Compliance audits pass only through manual workarounds.
We modernize the parts of a system that hold the business back, and leave working business logic in place. Our legacy modernization services span assessment, replatforming, refactoring, frontend, data, and support: full legacy system modernization services delivered by one team, starting from your codebase rather than a generic playbook.
A senior engineer audits the codebase, dependencies, and architecture, then produces a phased modernization roadmap with scope, risk map, and budget. This is also the entry point for modernization consulting when you need direction before committing to a build.
Best for: teams that need a defensible plan and cost before approving a project.
Modernization splits into six standard approaches, an R-based framework from Gartner's original strategies, later extended for the cloud by AWS (AWS, "6 Strategies for Migrating Applications"). The right approach depends on where the cost actually sits: infrastructure, code, or business logic.
Infrastructure is the bottleneck, the code is stable.
Low
You want cloud benefits without major code changes.
Low–Medium
High technical debt slows every release.
Medium
A monolith blocks scaling and needs service boundaries.
High
The code is unmaintainable and the business logic is outdated.
High
An off-the-shelf product covers the full requirement.
VariableMost real projects combine two or three of these across different modules. A reporting service might be rehosted while the order engine is rearchitected.
Modernization fails when it turns into a big-bang rewrite. We reduce that risk by changing the system in controlled increments, each one reversible.
1/6
We use AI where it measurably speeds up modernization, and nowhere that it would put delivery at risk. McKinsey found generative AI can cut roughly 20–30% off code-refactoring time and helps document undocumented legacy code (McKinsey, 2023).
AI accelerates analysis and routine refactoring, but every critical change is reviewed by senior engineers and architects. No AI-only delivery.
Where it helps on a legacy project:
As a modernization partner, we show you scope, cost, and risk at each phase, and you sign off before the next one starts.
1/4
The constraints differ by industry, and so does the modernization plan.
A manufacturer's legacy .NET app rebuilt into a responsive Angular and .NET WMS with FEFO picking, lot and bin tracking, and handheld scanning.
TwinCore built a custom AI agent platform for a US client: 14 reusable agent types for research, data extraction, analysis, and monitoring.
Our team successfully supported and enhanced a custom software solution for a US-based mental health clinic, focusing on improving operational efficiency, treatment tracking, and reporting capabilities. Designed for healthcare professionals, the platform streamlines the management of Electronic Health Records (EHR) and Electronic Medical Records (EMR) while adhering to strict HIPAA regulations.
The goal of this project was to design and implement a scalable, secure, and extensible backend system for automating the accounts payable (AP) lifecycle - from purchase requisition and approval workflows to invoice processing, supplier management, and payment scheduling.
Terminals is an innovative application developed to streamline the user registration process, leveraging a hybrid approach with cutting-edge technologies. Designed from scratch, the project focuses on delivering a seamless experience for users in Switzerland, allowing them to complete registration forms, generate certificates, and perform verification processes efficiently.
Teams hire .NET developers from TwinCore to work inside real, production systems rather than isolated tasks. Our developers join existing environments, take responsibility for defined areas, and contribute across backend, frontend, and infrastructure where needed.
| Before | After |
|---|---|
| Releases every 4–8 weeks | Deployments multiple times per week |
| Manual testing, regression risk | Automated test coverage, CI/CD |
| On-premise infrastructure, scaling pain | Cloud-native, auto-scaling |
| .NET Framework 4.x, no LTS support | .NET 8 with long-term support |
| Outdated UI, low user satisfaction | Modern React or Angular frontend |
| Security patches require manual work | Automated dependency updates |
| New developers take months to onboard | Documented, maintainable codebase |
| Compliance audits need workarounds | Audit-ready by design |
This is what makes an enterprise application modernization engagement predictable rather than a gamble: correct .NET version targets, honest legacy application modernization scoping, and a modernization roadmap you can hold us to. As an application modernization company, we keep the plan and the price tied together.
.NET expertise from .NET Framework through .NET 8, with version migrations as a standing service line.
We change only what needs to change and preserve working business logic, which keeps risk and cost down.
Modernizations delivered with full data preservation and guaranteed zero data loss across all completed projects.
Architects, developers, QA, DevOps, and modernization consultants in one team.
Weekly demos, clear milestones, and fixed-scope or time-and-materials models depending on the project.
Offices in Chicago and Tallinn cover both English-speaking client zones.
Legacy Software Modernization Engagement Models
Defined scope, predictable cost. Best for an initial technical audit and modernization roadmap.
We help companies upgrade outdated .NET, ASP.NET MVC, Web Forms, React, and Angular systems while preserving core business logic, data, and existing workflows. TwinCore modernizes legacy software step by step, so your product becomes easier to maintain, scale, and extend without a risky big-bang rewrite.
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