Top 13 .NET Development Companies In The UK (2025)

Let’s be honest. Finding the right .NET Development Company is tough.

Even a quick Google search hits you with 38,100,000 results. All promising the same things — enterprise-grade solutions, custom development, scalable architecture, cloud integration… you name it.

On top of that, there’s a massive range of services on offer. From building secure web applications and APIs to integrating with Microsoft Azure, creating custom CRM systems, or modernising legacy software — how do you know who’s actually great at what?

That’s exactly why we’ve put together this article: to give you a curated list of the most trusted, capable, and experienced .NET development companies that can help take your project from idea to implementation — without the headaches.

Ready to see the full list?

Let’s dive in.

What makes a top .NET Development Company?

You might be wondering — how did these companies make it onto our list?

We didn’t just Google “.NET development company” and pick the top few paid ads. That wouldn’t be helpful, and it definitely wouldn’t give you the best partners.

Instead, we went deep. We looked at real-world case studies, the technical capability of each team, client testimonials, long-term project success, and industry reputation.

Every .NET Development Company featured here has been thoroughly vetted — with real-world proof of delivering quality at scale.

So, what should you be looking for when choosing a .NET partner?

• Proven Technical Expertise: This isn’t just about knowing C#. It’s about architecture, scalability, security, and experience working across the .NET ecosystem — from ASP.NET Core to Azure integrations. Look at their past projects. Are they solving complex business problems or just building cookie-cutter apps?
• Clear Communication & Agile Processes: Is the team responsive? Do they walk you through their approach in simple terms? Strong communication and transparent workflows are essential. You don’t want a partner who disappears after the kickoff call.
• Industry Experience That Matches Yours: Are they experienced in your specific industry or use case? Whether it’s fintech, healthcare, logistics or SaaS — a company that already understands your challenges will deliver faster and better.
• Collaborative Fit: You’ll likely be working with them for several months (or more), so it’s essential you actually like the team. A strong cultural fit means better collaboration and fewer miscommunications down the line.
• Flexibility & Long-Term Support: Do they offer support post-deployment? Can they adapt if your scope evolves? A good .NET development partner isn’t just a one-and-done vendor — they’re a strategic asset for the long term.

As always, trust your gut — but back it up with facts and results.

Now that you know exactly what to look for, let’s get into the top .NET Development Companies in the UK that are actually worth your time.

Top .NET Development Companies

1. 6B

We’re proud to be recognised as one of the UK’s leading .NET Development companies — delivering robust, scalable, and secure software solutions for ambitious organisations.

Our .NET development capability is trusted by both the public and private sectors, and we’ve earned a strong reputation for delivering complex, enterprise-grade platforms through modern .NET technologies.

Some of our recent high-impact projects include work with the NHS, Sedgwick, ITV, and Greater Manchester Combined Authority — where we’ve developed high-performance systems handling millions of transactions, users, and data points.

But how exactly do we help businesses through .NET?

• .NET Development – Our team builds tailored solutions using .NET 6 and beyond, creating high-performing, scalable web applications, APIs, and complex integrations. Whether it’s a greenfield project or modernising a legacy system, we architect with longevity and maintainability in mind.
• Cloud Native & Azure-First Approach – As a Microsoft-focused consultancy, we leverage Azure’s full potential — from cloud-native infrastructure to containerisation, CI/CD pipelines, and application monitoring. That means your solution is scalable, secure, and future-ready.
• System Integration & Interoperability – We specialise in building systems that don’t just work in isolation, but integrate seamlessly with third-party platforms, national systems, and proprietary databases — using modern APIs and messaging frameworks.
• Agile Delivery – We deliver at pace through agile sprint-based development, giving you visibility, flexibility, and continuous progress. Our approach ensures stakeholder feedback is baked into every stage of delivery.
• User-Centred Design – We don’t just write clean code. We design with people in mind. Our in-house design and UX team ensures every solution is intuitive, accessible, and fit for real-world use.

We’re also proud to be a Crown Commercial Services supplier and a G-Cloud approved vendor — a reflection to our delivery standards, security posture, and project outcomes.

So, if you’re looking for a trusted .NET development partner who can deliver complex solutions at scale — let’s talk.

Get in touch with our .NET Development team

2. Ficode

A UK-based custom software development company with global reach, Ficode Technologies is highly regarded for its deep expertise in .NET development.

Ficode’s approach to .NET is all about building scalable, secure, and high-performance applications tailored to each client’s specific needs — whether that’s a startup looking for rapid development or an enterprise in need of digital transformation.

Their .NET development services cover everything from web apps and enterprise-grade platforms to API integrations and cloud-based solutions. They offer full-cycle development, including architecture design, UI/UX, testing, and ongoing support.

What sets Ficode apart is their flexibility and adaptability. They tailor their .NET services to suit businesses across sectors — from fintech and healthcare to eCommerce and telecom — without relying on a one-size-fits-all model.

If you explore their portfolio, you’ll see a proven track record with companies like Ernst & Young, Avanza Pharma, ABN AMRO, Mediphile, and more — demonstrating both technical capability and industry versatility.

So, if you’re after a .NET development partner with strong technical foundations and a pragmatic, client-focused approach — Ficode should absolutely be on your radar.

3. Blue Frontier

Blue Frontier is a UK based full-service digital agency with a strong specialism in .NET development, delivering robust and scalable software solutions to clients across both the private and public sectors.

Their .NET development services include:

• Custom .NET web applications
• Enterprise-level software solutions
• Bespoke CRM and CMS systems
• Legacy system redevelopment and modernisation
• API and third-party system integrations

Blue Frontier primarily works with Microsoft’s .NET framework to develop powerful, future-ready applications that meet the specific operational needs of their clients. Their in-house team of certified developers ensures security, scalability, and maintainability are built into every solution.

With experience delivering software for industries such as healthcare, government, finance, and education, Blue Frontier is trusted by clients like the NHS, UK police forces, and universities — proving their capability to handle complex and high-stakes projects.

So, if you’re looking for a dependable .NET development agency with enterprise experience and a strong technical backbone, Blue Frontier is a name worth knowing.

4. Innowise

Looking for a dedicated .NET development company with deep technical expertise? Innowise is a global software development firm that has been specialising in .NET solutions for over 15 years.

With a large team of over 400 .NET developers, Innowise focuses on building scalable, secure, and high-performance applications tailored to enterprise needs — from custom platforms and cloud-based systems to legacy software modernisation and cross-platform app development.

They offer end-to-end .NET development, covering architecture design, UX/UI, QA, DevOps, and long-term support — making them a one-stop solution for businesses looking to build or scale mission-critical software.

With offices in the UK, Innowise has worked with clients in healthcare, fintech, logistics, manufacturing, and beyond — proving their versatility and enterprise-grade capability.

5. UNL Solutions

UNL Solutions is a custom software development company with offices in the UK and with a dedicated focus on .NET development, offering end-to-end solutions for businesses of all sizes.

They specialise in building robust and scalable .NET applications — from enterprise-grade platforms and SaaS products to high-load systems and cloud-based solutions using Azure. Their developers work with ASP.NET, .NET Core, and a wide range of Microsoft technologies to deliver fast, secure, and efficient software.

What sets UNL apart is their ability to provide dedicated .NET development teams, tailored to client needs, which allows for flexible scaling and full control over the development process. They place strong emphasis on long-term partnerships and have experience across sectors like fintech, eCommerce, logistics, and more.

So, if you’re seeking a reliable .NET development company with proven technical depth and flexible engagement models, UNL Solutions is worth considering.

6. Cool Code Company

Based in Nottingham, Cool Code Company are specialists in .NET development, delivering high-performance web, desktop, mobile, and cloud applications tailored to modern business needs.

They build full-stack .NET solutions using technologies like ASP.NET Core, WPF, and .NET MAUI — with a strong focus on clean architecture, speed, and scalability. Whether you’re starting from scratch or modernising a legacy system, their team brings deep expertise in Microsoft technologies.

Cool Code also offers cloud-native development using Azure, API integrations, and CI/CD automation, with flexible support models to suit businesses of all sizes — from startups to enterprise-level organisations.

So, if you’re looking for a UK-based .NET development partner who can deliver secure, scalable, and fully integrated software solutions, Cool Code Company is a strong contender.

7. Systango

With offices in London and Indore, Systango are .NET development specialists focused on building high-performance, scalable software solutions for startups and enterprises alike.

Their .NET services include building custom web applications, enterprise platforms, cloud-native solutions on Azure, and API-driven backends — all tailored to meet specific business goals with speed and efficiency.

They’re a Microsoft Gold Partner and boast a strong track record, with clients ranging from PwC and Grindr to Deloitte and MGM — backed by glowing reviews and long-term partnerships.

8. BairesDev

With teams across the UK and North and South America, BairesDev are .NET development experts helping companies build secure, scalable, and high-performance applications.

Their .NET services include:

• Custom .NET software (web apps, mobile, desktop, even games)
• API & system integrations using ASP.NET Web API, WCF, Entity Framework
• Legacy migration and modernization (e.g. classic ASP → ASP.NET Core)
• E‑commerce platforms with secure payment and backend support
• Enterprise systems (ERP/CRM/BI) built on ASP.NET and Azure
• Cloud-native microservices on Azure/AWS/GCP using Docker, Kubernetes, Azure Functions

Recognised as a Microsoft Gold-level partner and trusted by over 500 clients since 2009, they’ve delivered more than 300 .NET projects—with a top‑1% talent pool of developers averaging 10+ years each.

9. Lilo

With teams based in London, Cape Town, and Perth, Lilo specialise in .NET development, crafting tailored software solutions for complex business challenges.

Their .NET services include:

• Dot NET Consulting – advising on architecture, best practices, performance optimisation and upgrades
• Product Development – full-cycle software creation using C#/.NET Core, from design to launch
• Upgradation & Migration – moving legacy apps (e.g., Web Forms, classic ASP) to modern .NET Core
• Integration Services – connecting systems via Web API, WCF, messaging queues and cloud integrations
• Lilo’s in-house developers cover the full Microsoft stack—from ASP.NET and Xamarin to WinForms/WPF—ensuring flexible deployment across web, desktop and mobile. They’ve built everything from financial tools like Mortgages for Business, to eLearning LMS (GymbaROO) and community platforms (My Pet Your Pet), all with a focus on performance, security, and maintainability.

Their process includes UX-led design, wireframing, full-stack development and post-launch support—mapping perfectly to your needs, whether you’re launching a new platform or modernising existing software.

So, if you’re after a geographically dispersed, experienced team to build, migrate, or integrate .NET-based systems with a user-first approach—Lilo is a compelling option.

10. ScienceSoft

Based in the UK and USA, ScienceSoft are seasoned .NET development specialists, delivering high-performance, secure, and scalable applications tailored to enterprise needs.

Their .NET services include:

• Custom .NET software solutions — web, desktop, mobile, IoT, and cloud platforms
• ASP.NET and ASP.NET Core development for enterprise apps, web portals, e‑commerce systems, and APIs
• Legacy modernization & migrations — rearchitecting legacy apps into microservices or cloud-native systems
• Outsourced development & team augmentation — dedicated .NET teams covering full-cycle development, QA, support, and DevOps

Cloud app development and optimization with CI/CD, infrastructure-as-code, and cost-efficiency

With over 20 years of .NET experience, 230+ completed .NET projects, and more than 60 certified .NET developers, they help clients reduce costs and accelerate delivery timelines. They’re ISO-certified and long-time Microsoft partners, with a focus on secure, compliant, and scalable development.

11. I-Finity

Having previously spoken to the I‑Finity team in York, we know first-hand the quality of work they produce for their .NET clients.

Not only do they deliver bespoke .NET web applications and modern SaaS platforms, but they also offer comprehensive Azure and Umbraco support — including architecture design, deployment, and ongoing cloud hosting management.

Their .NET services include:

• Custom web apps using ASP.NET Core
• Umbraco CMS development tailored to .NET projects
• Cloud-native SaaS platforms on Azure
• Legacy system migrations and modernisation
• Ongoing Azure hosting, support & DevOps

Their clients include Advanced Parking Tech, Doors Open Days, and South of Scotland Enterprise, all benefiting from scalable, secure, and fully supported .NET solutions.

So if you’re looking for a UK-based partner who can not only build, but also host and support your .NET systems end to end, I‑Finity is a good choice.

12. Blackthorn Vision

Blackthorn Vision, operating across the UK and the USA, are seasoned .NET development experts specialising in custom, enterprise-grade applications and solutions.

Their key .NET services include:

• Custom .NET software development – tailored web, desktop, mobile, and cloud apps
• ASP .NET & ASP .NET Core solutions – scalable web portals, APIs, and e-commerce systems
• Legacy system migration & modernisation – upgrading outdated platforms to modern architectures
• Integration & API development – seamless connectivity with internal and external systems
• Azure/cloud-native solutions – robust, scalable deployments and microservices
• Cross-platform apps with MAUI – unified mobile and desktop development

13. N-iX

N‑iX is a global software engineering powerhouse with offices in the UK and a sharp focus on .NET development, offering end-to-end services from bespoke web and API creation to high-performance enterprise, mobile, desktop, and cloud-native applications. With over 175 dedicated .NET developers working across 57 active projects, the company blends deep technical know‑how—covering ASP.NET Core, Blazor, WinForms/WPF, Xamarin/.NET MAUI—with scalable, secure solutions delivered from its 25 offices across Europe and the Americas . Their client list spans industries like finance, healthcare, manufacturing, logistics, and retail, with trusted names including Bosch, Siemens, eBay, Credit Agricole, TotalEnergies, and AVL.

If you’re seeking a partner that combines deep Microsoft-stack expertise with global delivery capabilities and flexible engagement models, N‑iX is a top contender.

Why Hire One of the Best .NET Development Companies?

With countless software development companies out there offering .NET services, choosing the right partner is crucial — the wrong decision can lead to wasted budget, missed deadlines, and underperforming systems.

That’s why selecting the right .NET development company is so important — it’s your chance to fast-track progress, minimise risks, and build software that actually delivers results.

Your business deserves a technology partner that understands your goals, works efficiently, and delivers reliable, scalable, and secure solutions. That starts with working with a team that specialises in the Microsoft tech stack and knows how to get the most out of .NET.

Sure, you’ll find cheaper options elsewhere — but those often come with hidden costs, delays, or underwhelming results. A low-cost build that doesn’t perform will cost far more in the long run.

So, if you’re looking for a proven .NET development partner to build custom applications, modernise legacy systems, or drive your digital transformation — we’re ready to help.

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