.NET Application Modernization Services

Your .NET systems still run the business. They also quietly hold it back. CHI Software's .NET application modernization services help you modernize legacy code without a risky full rewrite, moving it onto modern, cloud native .NET at a pace that corresponds to your risk tolerance. Assessment first, a pilot next, then incremental delivery you can actually measure.

OUR CLIENTS

When Legacy .NET Applications Raise Costs And Risk

A legacy .NET application rarely fails on a single day. It gets slower, more expensive, and harder to change, until one release cycle you notice the platform itself has become the constraint. Organizations on an aging stack tend to miss that shift because it happens gradually. The DORA report, drawing on nearly 5000 practitioners, makes a related point about AI: it amplifies whatever your engineering system already is. Bolt AI coding onto a shaky .NET codebase and you mostly speed up the mess. This technical debt becomes an active financial and security risk in November 2026, when official support ends for both .NET 8 and .NET 9, leaving businesses exposed to unpatched vulnerabilities, regulatory compliance failures, and soaring maintenance costs. Proactive .NET modernization is no longer just an IT chore. It is a time-sensitive strategic necessity to protect your operations and stay competitive.

Growing Maintenance Costs and Technical Debt
Do you notice how technical debt is piling up? It’s a very gradual process, and it’s hard to keep track of. The root cause of all this is your outdated platform: year after year, an ever-larger portion of your budget goes toward maintaining legacy systems. Meanwhile, new features go unfunded. According to GitClear, the number of duplicate code blocks in 2024 increased approximately eightfold due to the extensive adoption of AI tools, with “copy-paste” surpassing refactoring for the first time. Legacy .NET code, combined with the variable results of AI, is the cause of your losses.
Slow Releases and Limited Product Velocity
The release of updates is similar to the release of a full-fledged app. Why is that? When a single change affects multiple pages of the app, a legacy system can’t keep up with the new features. This affects your business’s competitiveness in the market: your competitors update weekly, while you update quarterly.
Outdated .NET Framework, Libraries, or Windows-Only Dependencies
The .NET Framework line (4.8 and earlier) is Windows-only and no longer gains new capabilities. Once your dependencies pin you to a specific Windows Server version or an unmaintained package, cloud native deployment, Linux hosting, and container platforms all stay out of reach until you modernize.
Security, Performance, and Scalability Risks
It’s very easy to attack a system running on outdated code. If an organization doesn’t maintain its runtime environment and NuGet packages properly, it’s automatically at risk. This leads to both performance limitations and an inability to scale. Imagine trying to scale a monolithic application without affecting the entire system — it’s impossible. And in regulated industries, you could face audit findings due to a lack of framework support.

Legacy .NET systems slow your team down before they slow your product down: find out which components carry the most risk before your next release cycle.

Get a Free .NET Technical Debt Assessment

What Our .NET Modernization Services Cover End-to-End

From first assessment to long term support, our .NET modernization services cover moving legacy applications off the .NET Framework and modernizing them for the cloud. That spans the full path technical, economic, and strategic buyers expect. Microsoft’s new agentic migration tooling (GitHub Copilot app modernization, replacing the deprecated Upgrade Assistant) accelerates dependency analysis and automated code transformation. We use these tools as part of our broad tech stack to reduce manual effort and speed up modernization, but the final architecture and migration decisions remain human-led and business-aligned.

.NET Application Assessment and Modernization Roadmap

We commence by thoroughly auditing your system. CHI Software analyzes the codebase, maps dependencies and flags blockers (like heavy System.web usage or legacy APIs). Next our team scores each module based on its business value. You get a clear modernization strategy that defines exactly what moves first, what waits and why.

.NET Framework to Modern .NET Migration

The CHI Software team is migrating applications from the .NET Framework to .NET Core. .NET Core is a modern, cross-platform framework that gives you greater control over your architecture. It’s important to us that your system never stops running, even for a moment, so we use the “Strangler Fig” pattern. This way, the new application runs in parallel with the old one and gradually takes over its functions.

ASP.NET, WCF, WinForms, WPF, and Windows Service Modernization

ASP.NET MVC and Web Forms, WCF services, WinForms and WPF desktop clients, Windows services: each has its own migration path. We choose the right one per component instead of forcing a single strategy across the whole estate.

Cloud, DevOps, Testing, and Observability Improvements

Modernization isn’t limited to code. Otherwise, it’s incomplete. Whether we restructure your system into a modular monolith to gain clean boundaries without the operational complexity of microservices, or leverage .NET Aspire to rapidly orchestrate and standardise cloud-ready, observable applications, the focus is on sustainable architecture. CHI Software integrates CI/CD pipelines, test automation, infrastructure as code, and deep telemetry to ensure that the modernized application deploys securely and remains measurable. In this way, you’re investing in a resilient engineering system, not just in tools to speed up coding.

.NET Modernization Approaches For Lower Risk And Faster ROI

There is no single “right” way to modernize. The choice depends on time constraints, the complexity of dependencies, and which parts of the business logic are still worth preserving. Microsoft notes that a phased migration is the standard, lower-risk option for most production applications built on ASP.NET, and we agree. A complete rewrite is the exception, not the starting point.

Rehost or Replatform When Speed and Lower Risk Matter
Migrating your system to the cloud is sometimes the fastest way to achieve your business goals. Another option is to perform a simple migration to containers, postponing more extensive changes to the code. That way, you’ll save money and get Linux-based hosting if you can’t make changes to the business logic just yet.
Refactor When the Core Business Logic Is Still Valuable
Sometimes the framework becomes outdated, but the business logic is still important and must be preserved. In such cases, our team opts for refactoring. This involves migrating to .NET Core, implementing dependency injection, and simplifying data access. We also preserve the behavior that your users have come to rely on.
Rearchitect or Rebuild Critical Modules When Legacy Code Blocks Growth
If certain modules of your system need to be modernized, we rely on a redesign, or our team completely rebuilds them. Note that a complete rewrite carries greater risk. However, we choose this approach only when the benefits are clear.

Our .NET App Modernization Process for Minimal Disruption

Our .NET app modernization process gives CTOs technical clarity, CEOs a predictable budget, and CIOs the governance and change control they answer for.

For over 20 years, we’ve adopted a phased approach that allows us to maintain control at every step.

Discovery and Technical Assessment
CHI Software team profiles the codebase, dependencies, data access patterns, and runtime constraints, then agree on what success looks like in numbers.
Stage result
- technical assessment report
Modernization Strategy and Roadmap
At this stage, the modernization strategy takes shape. We determine the sequence of steps, the methods we’ve chosen for each module, and also how much it will cost and how long it will take.
Stage result
- detailed .NET modernization roadmap
Pilot Modernization
CHI Software’s engineers modernize a low-risk slice first. We migrate simple, stateless routes before anything critical. The pilot proves the approach on your real code, not a slide.
Stage result
- functional, modernized slice of the application successfully running in the new environment
Incremental Implementation and Testing
Module by module, behind the Strangler Fig proxy, each increment ships with automated tests and a working fallback to the legacy path if something misbehaves.
Stage result
- core application modules
Rollout and Post-Launch Optimization
We don’t walk away after implementation. The CHI Software team stays with you to complete the transition, gradually phase out legacy components, and improve performance. As soon as new traffic starts coming in, you’ll be ready.
Stage result
- fully modernized, high-performance platform handling 100% of production traffic

We scope the first migration milestone in two weeks so your team has a fixed cost, a clear timeline, and a rollback plan before any code changes.

Request a Fixed-Scope Modernization Pilot

Business Benefits of .NET Application Modernization

Lower Maintenance and Infrastructure Costs Windows Server licensing fees and expensive on-premises infrastructure maintenance costs will persist as long as you run legacy systems on the .NET Framework. Migrating to modern .NET solves this problem. You can run applications in lightweight Linux containers, achieving up to 40–50% infrastructure cost savings and reducing your OPEX.
Faster Release Cycles and Better Developer Productivity Implementing modern CI/CD practices and automation tools frees developers from routine manual deployment and testing processes. Research from GitClear shows that the unguided use of AI assistants often leads to duplicate code blocks. Structured modernization and strict testing discipline eliminate this risk.
Stronger Security and Easier Compliance Updating the platform grants access to advanced built-in security mechanisms, current encryption schemes, and regular security patches. This simply not only reliably protects corporate and client data but also notably simplifies passing international technical audits and complying with modern regulations (such as GDPR, PCI DSS).
Better Performance, Scalability, and Cloud Readiness After modernization, your application becomes a true cloud-native solution. By boosting data access and overall performance, the system gains the ability to scale dynamically and automatically according to real-time traffic demands.
Easier Integration With APIs, Data Platforms, and AI Tools A modernized .NET platform smoothly interacts via REST API or gRPC with any external solutions, modern data platforms (such as Databricks, which we partner with), and advanced AI-powered tools.
Better Budget Predictability And Executive Visibility The modernization process breaks down into clear, measurable phases with fixed outcomes. This gives the business and executive stakeholders full visibility: you see exactly where funds are invested, which technical debts are prioritized, and what financial or operational return each iteration brings. Instead of unpredictable expenses spent on “putting out fires” in legacy code, you get a managed and predictable budget.

For organizations already on .NET 8, the upcoming end-of-support date creates a governance deadline: production workloads on unsupported runtimes expose the organization to audit risk. A structured .NET 10 migration roadmap closes that gap before the deadline.

Your board needs a business case, not a technical plan: we deliver a roadmap with projected OPEX savings and delivery milestones ready for executive review.

Get a Board-Ready Modernization Roadmap

Why Choose CHI Software for .NET Modernization

Legacy System Experience, Not Just New Development

Our legacy software modernization experience includes working with complex .NET code, understanding the logic of systems built years ago, and carefully migrating these systems into a modern environment.

Assessment-First Approach Before Any Rewrite Decision

CHI Software will not quote a rewrite before we have read your code. Every engagement opens with assessment, because the wrong approach chosen early is the expensive one.

Incremental Delivery With Minimal Business Disruption

We rely on a phased modernization approach. For you, this is a predictable and measurable process. The migration, phased implementation, and rollback plans for the “Strangler Fig” system ensure that your business continues to operate smoothly during the modernization process.

Application, Cloud, DevOps, and QA Expertise in One Team

Application, cloud, DevOps, and QA sit on one team, so you are not stitching together five vendors and refereeing their finger-pointing when something breaks.

Long-Term Support After Modernization

We stay on after go-live with managed services and long term support, keeping the modernized platform patched, tuned, and healthy as your product grows.

Our Awards and Certifications

.NET Modernization Case Studies

All cases

Digital E-Learning Platform for Kids

Through gamification, UX redesign, and backend optimization, CHI Software turned a struggling product into a user favorite — boosting satisfaction by 40% and enabling worldwide expansion.

Database and Data Security Solution

Our client delivers innovative database and data security software to customers worldwide. The company implements real-time monitoring, data masking, and sensitive data discovery, and secures sensitive data everywhere in the

DSD Software Modernization

Through step-by-step modernization, CHI Software transformed a legasy DSD platform into a scalable, efficient tool — achieving 97% retention and faster, smoother logistics.

To deliver the project on time, the CHI Software team stepped above the time limits and demonstrated high personal engagement. The technical level of the team and management was beyond our expectations. We will surely continue our cooperation in the future.

Shigenori Sato

Founder at Pax Creation Asia

The CHI Software team were able to implement several applications in the app that were in accordance with the requirements of the client. This allowed them to speed up and simplify the interface and make it more comfortable to use. The team's workflow was efficient.

Andriy Fedorenko

COO at Soft Industry Alliance

We were in search of a talented team to develop a compelling product, and we were fortunate enough to have discovered CHI Software. With expert advice and guidance, they surpassed our expectations, transforming our concept into a stunning reality. Not only are their staff knowledgeable in their craft, but their professionalism is second to none. I highly recommend the services that CHI Software has to offer and look forward to future collaborations.

Peter K. Tran

CEO at PrismTechInc

One assessment covers architecture, dependencies, compliance risk, and cloud readiness so every stakeholder starts from the same facts.

Book a .NET Modernization Assessment

FAQ

What is .NET application modernization?

It is the work of moving a legacy .NET application, usually on the Windows-only .NET Framework, to modern, cross-platform .NET, and improving its architecture, security, and cloud readiness along the way. It ranges from a simple rehost to a full rearchitecture, depending on the state of the code.
When should a company modernize a .NET Framework application?

When maintenance keeps eating the budget, releases keep slowing, security or compliance flags an unsupported runtime, or the framework blocks your cloud and AI plans. If any two of those are true, it is time to modernize.
How long does .NET application modernization take?

It all depends on the specific state of your system. If we need to refactor it, that will take a few weeks. But if our goal is to migrate a large system that also needs to remain operational at all times, the work will take several months.
What is the difference between rehosting, replatforming, refactoring, and rearchitecting?

Rehosting is the process of migrating with minimal changes to the code. Migrating to a new platform (replatforming) involves making minor changes to adapt to the cloud environment. Refactoring is the restructuring of code while preserving its behavior. Architecture redesign is the reworking of a system, which often involves breaking down a monolithic system into services.
How do you reduce risk during .NET modernization?

To minimize the risks of .NET app modernization, an assessment must be conducted first. This should be followed by a pilot project, provided that it involves a low level of risk. Next, the system must be implemented in phases using a proxy server (Strangler Fig), tests must be run, and a rollback plan must be developed — this plan must be in place before deployment.
How do you measure the success of a .NET modernization project?

Against metrics you set upfront: deployment frequency and change lead time (the DORA measures), maintenance cost, incident rate, performance, and infrastructure spend. Modernization you cannot measure is not really finished.