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1. Assess and inventory
We map the code, NuGet packages, databases, integrations and hosting. Tools such as the .NET Upgrade Assistant and portability analysis show what blocks an upgrade.
.NET Legacy System Modernization Company
Legacy .NET system modernization means upgrading ageing .NET Framework applications to a current .NET release, such as .NET 10 LTS, and moving them to cloud-ready architecture without stopping the business. PerfectionGeeks, based in Gurugram, India, does this in phases: assessment, refactoring, re-platforming, API and database updates, and testing. Projects start at $15,000 for small applications.
12+Years Building Software
200+Projects Delivered
4.9/5Clutch Rating (45+ Reviews)
- Target: .NET 10 is the current LTS release (November 2025). .NET 8 support ended on 10 November 2026, so apps still on it need a plan.
- Legacy .NET Framework: version 4.8 is in maintenance mode and gets no new features. Web Forms and WCF servers have no direct port to modern .NET.
- Method: PerfectionGeeks modernizes in phases, so the live system keeps running while modules move one at a time.
- Price: assessment and refactoring of small apps starts at $15,000. Migration and cloud adoption starts at $30,000. Large programs are quoted after a free consultation.
- Team: an in-house team in Gurugram, India, with 12+ years of software experience and 200+ projects delivered.
Which .NET modernization approach should you choose?
Most legacy .NET systems need a mix of these approaches, applied module by module. The assessment decides the mix.
| Approach | What changes | Best when | Effort and risk |
|---|---|---|---|
| Rehost (lift and shift) | The app moves as-is to cloud virtual machines or a new data centre | You must exit old hardware fast | Low effort. Technical debt stays. |
| Replatform | The app moves to managed services such as a managed database or app hosting, with small code changes | The code is healthy but the hosting is not | Low to medium effort |
| Refactor and upgrade | Code is ported from .NET Framework to current .NET, using ASP.NET Core and EF Core | The business logic is sound but the framework is old | Medium effort. Library and API gaps must be checked. |
| Rearchitect | A monolith is split into modules or services, often with the strangler fig pattern | One part of the system limits scale or release speed | Medium to high effort. Lower risk when phased. |
| Rebuild | The app is rewritten on a modern stack | The code is unmaintainable or tied to unsupported components | High effort and cost |
| Replace | A packaged or SaaS product takes over the function | The function is a commodity, not a differentiator | Varies. Data migration is the main risk. |
.NET Framework vs modern .NET: key differences
| Area | Legacy .NET Framework | Modern .NET (.NET 10 LTS) |
|---|---|---|
| Platform | Windows only | Windows, Linux, macOS and containers |
| Web apps | ASP.NET Web Forms, MVC 5, Web API 2 | ASP.NET Core, Razor Pages, Blazor, minimal APIs |
| Service layer | WCF and .NET Remoting | REST and gRPC; CoreWCF can carry existing WCF contracts |
| Data access | Entity Framework 6, ADO.NET | EF Core, Dapper, ADO.NET |
| Hosting | IIS on Windows Server | Docker, Kubernetes, managed cloud hosting, or IIS |
| Support status | Version 4.8 is in maintenance mode, with no new features | The current LTS release. .NET 8 support ended 10 November 2026. |
How does PerfectionGeeks modernize a legacy .NET application?
02
2. Plan the phases
We rank modules by business value and risk. You get a phased roadmap, a target architecture and a quote.
03
3. Refactor and upgrade code
We port code to current .NET without changing external behavior. Web Forms screens and WCF services are replaced where no direct port exists.
04
4. Modernize APIs and data
We expose clean REST or gRPC APIs and update the database schema, queries and data access layer. Legacy and new modules run side by side.
05
5. Test at every phase
Automated unit, integration and regression tests confirm that behavior matches the old system before each cutover.
06
6. Deploy and hand over
We deploy with CI/CD to your cloud or servers, monitor the release and train your team. Retire old components only after the new ones are stable.
What .NET modernization services do we offer?
Application assessment
A written review of code health, dependencies, security gaps and migration options, with priorities and a phased plan.
.NET Framework to .NET 10 upgrade
Port ASP.NET MVC, Web API, Windows services and class libraries to current .NET, including ASP.NET Core and EF Core.
Web Forms and WCF replacement
Rebuild Web Forms screens in Blazor or Razor Pages. Move WCF services to REST, gRPC or CoreWCF.
Cloud migration
Containerize with Docker and deploy to Azure, AWS or Kubernetes with CI/CD pipelines and monitoring.
API modernization
Wrap legacy logic in secure, versioned APIs so new apps and partners can connect. See our API development and integration service.
Database modernization
Upgrade SQL Server, clean up schemas, tune slow queries and move data access to EF Core, with verified data migration.
How much does .NET legacy system modernization cost?
Cost depends on code size, framework gaps, integrations and data volume. Dedicated developers start from $25 per hour. Yearly maintenance after launch is usually 15-20% of build cost.
| Package | Starting price | What is included | Best for |
|---|---|---|---|
| Basic | From $15,000 | Initial assessment and refactoring to improve performance and security | Small applications |
| Standard | From $30,000 | Application migration and cloud adoption, with scalability and integration work | Medium-sized applications |
| Premium | Quoted after a free consultation | Full API modernization, advanced database work and phased migration to limit downtime | Large, multi-module systems |
What are the main risks of modernizing a .NET application?
What are the main risks of modernizing a .NET application?
Why Businesses Choose PerfectionGeeks
Why Businesses Choose PerfectionGeeks
Related Services
Related Services
Get a free .NET modernization assessment
Tell us about your legacy .NET application. PerfectionGeeks will review it and suggest a phased plan with a quote.
Client Testimonials
PerfectionGeeks provided excellent service from start to finish. Their team was professional, easy to work with, and delivered exactly what we needed on time. We’re very pleased with the outcome and would gladly recommend them to others.
Thanaboon Mingkaew
CEO, SMART IOT
We partnered with PerfectionGeeks for a custom accounting automation software, and the experience was excellent. Their team delivered a high-quality solution that streamlined our operations and improved efficiency. Professional, skilled, and reliable — we’re already working with them on another project.
Saarthak Gupta
Founder, Ceos Accounting Services
As COO of TRP Construction Management, I’m proud of our growth from 300 to 16,000+ SKUs and 4,000+ vendors since 2022. Thanks to Shrey Bhardwaj and Perfection Geeks for delivering scalable, future-ready technology solutions that transformed our vision into a seamless pan-India platform. Highly recommended technology partner.
Mayank Pathak
COO, TRP Construction Management
PerfectionGeeks Technologies transformed our vision into reality with innovative technology solutions. Their professionalism, timely delivery, transparent communication, and commitment to quality made the entire collaboration smooth, reliable, and highly satisfying.
Armaan
Cofounder, Kzminer
I highly recommend PerfectionGeeks Technologies for mobile and web development services. Their expertise, dedication, creative ideas, and customer-focused approach helped our business achieve impressive digital growth successfully.
Chetna
Founder CEO , Klicked
Choosing PerfectionGeeks Technologies was the best decision for our company. Their skilled developers created a user-friendly platform, provided constant assistance, and ensured exceptional performance beyond our expectations every step.
Mark
CTO, IMSMART
Working with PerfectionGeeks Technologies was an excellent experience. Their team delivered our project on time with outstanding quality, smooth communication, innovative solutions, and professional support throughout the entire development process.
Naveen
Founder Director , Way2Kart
PerfectionGeeks Technologies delivered a smooth, professional experience with excellent communication and technical expertise. Their team understood project requirements clearly, provided timely updates, and ensured high-quality results that exceeded expectations.
Srinivasa Mothay
CTO, Sethu Fishries
PerfectionGeeks Technologies impressed with their innovative solutions, responsive support, and commitment to quality. The team handled every detail professionally, delivered on time, and created a seamless experience from start to finish.
Mervin
Cofounder & CTO, Clover Infinity
Frequently Asked Questions
What are the main approaches to .NET legacy system modernization?
The main approaches are rehost, replatform, refactor and upgrade, rearchitect, rebuild and replace. Most projects combine several, moving module by module. An assessment shows which approach fits each part of your system.
How much does .NET legacy modernization cost?
At PerfectionGeeks, assessment and refactoring of small applications starts at $15,000, and migration with cloud adoption starts at $30,000. Large, multi-module programs are quoted after a free consultation.
Should we upgrade from .NET Framework to .NET 10?
Yes, in most cases. .NET 10 is the current LTS release, while .NET Framework 4.8 is in maintenance mode with no new features. Modern .NET also runs on Linux and in containers, which lowers hosting cost and widens your options.
Can legacy .NET Web Forms and WCF apps be migrated?
Not directly. Web Forms has no port to modern .NET, so screens are rebuilt in Blazor or Razor Pages. WCF services can move to REST or gRPC, or run on CoreWCF if clients must keep existing WCF contracts.
How long does .NET legacy system modernization take?
It depends on code size, framework gaps, integrations and data volume. A small app can move in a single phase, while large systems run in several. PerfectionGeeks gives a phased timeline after the assessment, not before.
Can the system stay live during modernization?
Yes. We use a phased approach in which old and new modules run side by side, often with the strangler fig pattern. Traffic moves to each new module only after testing confirms it matches the old behavior.
Do we have to move to the cloud when modernizing?
No. Cloud migration is an option, not a requirement. Upgraded .NET apps can run on your own servers. We recommend cloud hosting when you need elastic scale, faster releases or lower infrastructure cost.