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.NET Applications for Serious Business Workloads

ASP.NET Core APIs, enterprise web apps and Azure services in C#, plus migrations from legacy .NET Framework to modern .NET.

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Program.cs
Sample code

.NET development for enterprise reliability

Modern .NET is Microsoft's open-source, cross-platform framework for building web apps, APIs, background services and desktop software in C#. ASP.NET Core performs very well, runs on Linux or Windows, and integrates closely with Azure, SQL Server and Microsoft 365. Strong typing, mature tooling and long-term support releases make it a dependable foundation for systems that must run for many years.

.NET is the natural choice when your organisation already uses Microsoft technologies, when you need tight Active Directory or Office integration, or when you run Windows desktop software alongside web systems. For startups optimising for hiring speed and JavaScript-heavy teams, Node.js may be simpler. For teams standardised on Java, Spring Boot is the equivalent path.

Nexzem builds new ASP.NET Core applications and modernises older ones. A large part of our .NET work is moving Web Forms, WCF and .NET Framework apps to current .NET, which brings better performance, Linux hosting and container support. We plan these migrations module by module, with tests, so business operations are never put at risk.

Read .NET, the way we write it

A short, idiomatic sample. Scroll and the editor types each part while the note beside it explains why it is written that way.

Program.cs
Sample code
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddDbContext<ShopDb>(o => o.UseNpgsql(builder.Configuration.GetConnectionString("Shop")));
builder.Services.AddHealthChecks();
var app = builder.Build();
// Minimal API: a route, its dependencies and a typed result
app.MapGet("/orders/{id:int}", async (int id, ShopDb db) =>
// EF Core turns this into one parameterised query
await db.Orders.FindAsync(id) is { } order
? Results.Ok(order)
: Results.NotFound());
// Health endpoint for the load balancer
app.MapHealthChecks("/healthz");
app.Run();

  1. line 7-8

    Minimal API: a route, its dependencies and a typed result

  2. line 9-13

    EF Core turns this into one parameterised query

  3. line 14-17

    Health endpoint for the load balancer

What we build with .NET

Enterprise .NET applications, APIs and cloud services in C#, including upgrades from legacy .NET Framework.

  1. 01

    ASP.NET Core Web APIs

    Fast, versioned REST and gRPC APIs in C# with authentication, validation and OpenAPI documentation for web, mobile and partner integrations.

  2. 02

    Enterprise Web Applications

    Line-of-business systems with complex workflows, approvals, reporting and role-based access, built on ASP.NET Core with SQL Server or PostgreSQL.

  3. 03

    .NET Framework Migration

    Planned moves from .NET Framework, Web Forms and WCF to modern .NET, preserving business rules while gaining performance and container hosting.

  4. 04

    Blazor Applications

    Interactive web UIs written in C# with Blazor, letting .NET teams build rich frontends without switching to a JavaScript framework.

  5. 05

    Azure Cloud Services

    Azure App Service, Functions, Service Bus and Azure SQL setups for .NET workloads, with infrastructure as code and CI/CD pipelines.

  6. 06

    Microsoft 365 Integration

    Single sign-on with Entra ID, plus Microsoft Graph integrations for Outlook, Teams and SharePoint data inside your applications.

  7. 07

    Desktop and Background Services

    WPF and WinForms maintenance, Windows services and worker services that process files, queues and scheduled jobs reliably, with logging and restart behaviour suited to unattended operation.

Why teams pick Nexzem for .NET

The checks every engagement has to pass before we call it done.

.github/PULL_REQUEST_TEMPLATE.md5/5 checked

  • - [x] Long-term stability

    LTS releases and strong typing suit systems expected to run for a decade.

  • - [x] Fits Microsoft environments

    Native integration with Azure, SQL Server and Microsoft 365 reduces glue code.

  • - [x] High performance

    ASP.NET Core handles heavy API traffic efficiently on modest infrastructure.

  • - [x] Lower hosting options

    Modern .NET runs on Linux and containers, opening cheaper hosting choices than Windows-only servers.

  • - [x] Careful migrations

    Module-by-module modernisation keeps legacy systems running while they improve.

Moving from .NET Framework to modern .NET

.NET Framework 4.8 is the final version of the original Windows-only framework. It remains supported as part of Windows, but it receives no new features, and modern libraries increasingly target only current .NET. Modern .NET runs on Windows, Linux and macOS, performs significantly better, works well in containers and ships long-term support releases every two years, each supported for three years.

Many applications can move with moderate effort using Microsoft's upgrade tooling, especially class libraries, console apps, ASP.NET MVC and Web API projects. The harder cases are technologies that did not carry over directly: ASP.NET Web Forms has no direct successor and usually means rebuilding screens in Razor Pages, MVC or Blazor, and WCF services move to CoreWCF, gRPC or REST APIs.

A realistic plan starts with an inventory of projects and dependencies, upgrades shared libraries first so they target both frameworks, and then moves applications one at a time. Running old and new side by side behind the same gateway avoids a risky single cutover and lets each team move when ready. Shared libraries targeting both frameworks make this possible.

How we structure a .NET solution

We usually separate a solution into domain, application, infrastructure and API projects, so business rules do not depend on databases or web frameworks. APIs are built with ASP.NET Core minimal APIs or controllers, validation with FluentValidation, and data access with Entity Framework Core and versioned migrations, or Dapper where raw SQL performance matters. This separation keeps tests fast.

Configuration uses the options pattern with secrets in Azure Key Vault or another vault, logging uses structured logs with OpenTelemetry traces, and health checks feed load balancers and monitoring. Background work runs in hosted services or a job library, and integration tests run against real databases in containers through Testcontainers. Each of these is wired up once in a shared template for new services.

  • Clear project boundaries for domain, application and infrastructure.
  • Dependency injection with the built-in container.
  • EF Core migrations reviewed like code.
  • Structured logging and distributed tracing.
  • Automated tests at unit and integration level in CI.

Cost drivers of a .NET project

Beyond development effort, .NET projects carry some specific cost factors. Licensing choices such as Windows Server and SQL Server editions versus Linux hosting and PostgreSQL can change running costs considerably, and migration scope depends heavily on how much legacy technology the application uses. Clarifying these early avoids surprises in both the build and the monthly bill. A short discovery phase usually clarifies them.

  • Amount of Web Forms, WCF or other legacy technology to replace.
  • Database and operating system licensing choices.
  • Integrations with Microsoft 365, Entra ID and line-of-business systems.
  • Hosting model: App Service, containers, Kubernetes or on-premises.
  • Security, audit and compliance requirements.
  • Test coverage of the existing system before changes begin.
  • Training for teams moving from Windows-only tooling.

How .NET projects run

$ git log --graph --oneline main..delivery

  1. b13d6b5

    feat: assessment

    We review existing .NET code, dependencies, infrastructure and integration points.

  2. 46bed39

    feat: architecture and plan

    Target architecture, hosting and migration or build phases agreed with stakeholders.

  3. d0ab972

    feat: incremental delivery

    Features or migrated modules delivered in sprints with automated tests.

  4. fa50fd4

    feat: cutover and hosting

    Deployment to Azure or your environment with monitoring and rollback plans.

  5. 2f8d76f

    merge: ongoing support

    Patching, .NET version upgrades and enhancements under a support agreement.

What teams build with .NET

  • Replacing WCF services

    An enterprise's internal WCF services are rebuilt as gRPC and REST APIs on modern .NET, running in containers on Linux, while existing clients are migrated gradually through a compatibility layer that keeps operations running smoothly throughout.

  • Blazor internal application

    A company's .NET team builds an internal operations portal in Blazor, sharing C# models and validation between frontend and backend, so developers deliver rich interactive screens without a separate JavaScript framework to learn and maintain.

  • Microsoft 365 and Teams integration

    Approvals, notifications and documents from a line-of-business system appear inside Microsoft Teams and Outlook through the Microsoft Graph API, with single sign-on through Entra ID, so employees act without switching between applications.

  • ERP connector service

    A .NET background service synchronizes orders, inventory and invoices between an ecommerce platform and the company's ERP, with retries, error queues and dashboards that show finance teams exactly which records failed and why.

  • Windows service moved to containers

    A legacy Windows service that processes files overnight is rewritten as a .NET worker running in containers on Linux, with monitoring, automatic restarts and horizontal scaling replacing a single fragile server in the office.

Where .NET sits in your stack

The tools we pair it with, layer by layer. Select a layer to see what it is responsible for.

Technologies often used with .NET

All 32 technologies

More in Backend

.NET development FAQs

Something else on your mind? Ask a consultant and get a reply within one business day.

When is .NET better than Java or Node.js?

.NET fits best when you already use Microsoft products, need Windows or Office integration, or want strong typing with excellent tooling. Java suits organisations standardised on the JVM, and Node.js suits JavaScript-centric teams. We recommend based on your environment.

Should we move from .NET Framework to modern .NET?

.NET Framework still receives security fixes but no new features. Modern .NET is faster, runs on Linux and containers, and gets regular improvements. For actively developed systems, migration usually pays off over time.

What drives .NET project cost?

Cost depends on system size, integrations, migration complexity, Web Forms or WCF usage, test coverage and hosting changes. A fixed quote follows a free consultation and code review.

Do you work only on Azure?

No. .NET apps run well on AWS, Google Cloud and on-premise servers too. We deploy wherever suits your cost, compliance and existing contracts.

How do you handle security and compliance?

We use ASP.NET Core identity and authorisation features, Entra ID single sign-on where needed, encrypted secrets, audit logging and patched dependencies. NDAs are available on request.

Can .NET applications run on Linux?

Yes. Modern .NET runs on Linux, Windows and macOS, and many production .NET services run in Linux containers on Kubernetes, Azure App Service or AWS. Applications on the older .NET Framework need migrating first, since that framework runs only on Windows.

What happens to our ASP.NET Web Forms application?

Web Forms is not available on modern .NET, so applications need a plan. Options include keeping it on .NET Framework while isolating and securing it, or rebuilding screens gradually in Razor Pages, MVC or Blazor while sharing business logic moved into modern class libraries.

We work with clients across the USA, UK, Australia, UAE, New Zealand and India.

Where we work

Tell us what you're building.

A solutions consultant replies within one business day with a recommended stack, a rough estimate and a suggested team.

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