ASP.NET Core APIs
Minimal APIs or controllers with OpenAPI documentation, versioning, rate limiting and sign-in through Microsoft Entra ID or your own identity provider.
C# and .NET development company · UK
C# and .NET Development Company in the UK
Work with a UK-focused C# and .NET development company for stable APIs, reliable data flows, and production services your product can grow on. Techsleight Labs plans, designs, builds, QA-tests, launches, and supports production software with senior engineers, weekly demos, and clear delivery ownership.
- Strategy, build, QA and launch in one team
- Fixed-price projects after discovery
- Code and IP owned by you
Capabilities
C# and .NET capabilities we bring to your product.
At home in modern .NET, and unfazed by the Web Forms, WCF and .NET Framework 4.x code that still runs many UK line-of-business systems.
Blazor web apps
Interactive UIs written in C#, with server, WebAssembly or static rendering chosen per page — a strong fit for internal tools built by a .NET team.
Entity Framework Core
Clean models and migrations, plus the unglamorous fixes — N+1 queries, missing indexes, needless change tracking — that make a slow EF app quick again.
.NET Framework to modern .NET
Incremental migrations that route pages to ASP.NET Core through a YARP proxy, so old and new run side by side until the last route has moved.
Azure-hosted applications
If you are on Azure: App Service, Functions, Azure SQL, Service Bus and Key Vault, defined as infrastructure as code. On AWS or containers, the .NET work is the same.
Microsoft 365 and Dynamics
Microsoft Graph for Outlook, Teams and SharePoint, and the Dataverse and Business Central APIs for Dynamics 365, syncing customers, cases and documents.
What we build
What we build with C# and .NET.
Typical .NET work for UK teams, from customer-facing APIs to the internal systems finance and operations staff use all day.
Line-of-business web apps
Case management, approvals, scheduling and reporting in ASP.NET Core or Blazor, with the role-based access and audit history operations teams rely on.
Windows desktop modernisation
Move WinForms and WPF apps onto modern .NET so they keep receiving fixes — or replace the screens people use most with a web front end.
Teams and Outlook add-ons
Teams apps, Outlook add-ins and background syncs backed by Microsoft Graph, so work gets done in the tools staff already have open.
Dynamics 365 integrations
Keep accounts, orders and cases in step between Dynamics 365 and your website, ERP or finance package, with retries and a log of every change.
Multi-tenant SaaS back ends
Tenant isolation, subscriptions, background jobs and public APIs on ASP.NET Core, ready to host on Azure, AWS or plain containers.
WCF and Web Forms retirement
Replace WCF services with REST or gRPC — or CoreWCF where clients cannot change — and rebuild Web Forms pages in Razor Pages or Blazor, screen by screen.
Technology stack
Technology stack.
The tools that usually sit around C# and .NET in the projects we join. We fit into your stack — this is where we are most at home.
Core
C# and modern .NETASP.NET CoreBlazorSignalR
Data
Entity Framework CoreDapperSQL Server and Azure SQLPostgreSQL
If you are on Azure
App ServiceAzure FunctionsService BusKey Vault
Microsoft ecosystem
Microsoft GraphEntra IDDynamics 365 and DataversePower Platform connectors
Testing
xUnit and NUnitbUnit for BlazorPlaywrightTestcontainers
Hosting and delivery
Docker and KubernetesAWSGitHub ActionsAzure DevOps Pipelines
Pricing
C# and .NET development pricing.
Start with discovery, move to a fixed-price build, or run a dedicated team for a longer roadmap.
C# and .NET discovery sprint
From £2,000
Architecture, roadmap, cost planning, and project-risk validation
- A short strategy sprint covering technical scope, user flows, delivery plan, and budget range.
Managed C# and .NET development project
Fixed quote
MVPs, rebuilds, SaaS platforms, dashboards, portals, and business-critical launches
- Product planning, UX, engineering, QA, deployment, and post-launch support under one delivery owner.
Dedicated C# and .NET development team
From £9,500 per month
Longer roadmaps, multi-sprint delivery, and product teams that need extra senior capacity
- A stable engineering pod with weekly demos, sprint planning, code review, and transparent reporting.
Prices are in GBP. Every estimate is confirmed in writing after a discovery call — the figures above are where engagements start, not a quote.
How we deliver
How we deliver your C# and .NET project.
Seven stages, the same on every project. The length of each one changes with the work; skipping one never saves time for long.
- 01
Product and technical discovery
We map your C# and .NET product goals, users, integrations, compliance needs, timeline, and commercial priorities before planning the build.
Goals, users and constraints agreed
- 02
Architecture and delivery plan
You get a practical C# and .NET roadmap with milestones, team shape, risks, estimates, and the first release path.
Roadmap, team and estimate
- 03
Design, build, and QA
Our team ships the C# and .NET product in controlled sprints with code review, testing, demos, and visible progress every week.
Tested software every sprint
- 04
Launch and improvement
We handle deployment, analytics, monitoring, handover, and post-launch iterations so your C# and .NET platform keeps improving.
Live, monitored and documented
Why Techsleight
What working with us is actually like.
No inflated numbers — just how we run projects, and what you can hold us to.
Product engineering, not ticket-taking
We ask what the software is for before we estimate it — and we will tell you when something should not be built, or should be bought instead.
AI where it earns its place
LLM features, retrieval and automation built with evaluation, guardrails and cost controls, and plain software where that is the better answer.
Full-stack under one roof
Design, frontend, backend, mobile, cloud and QA in one team, so nothing falls between suppliers.
UK-focused delivery
UK business hours, estimates in pounds, and a contract with a UK company. Our engineers are based in the UK and India.
Flexible engagement
A fixed-scope project, dedicated developers or a monthly retainer — and you can move between them as the work changes.
You own everything
Code, IP, cloud accounts and documentation are yours from day one. We sign an NDA before discovery if you need one.
Support after launch
We stay on for fixes, upgrades and new features, or hand over cleanly to your in-house team with the documentation to match.
Relevant work
Related product work.
We do not have a published C# and .NET case study yet — these show the kind of product work our engineers join.
All case studiesEducation · SaaS
University Management
University management system replacing spreadsheet enrolment and timetabling.
ReactNode.jsPostgreSQLAWS
Read the case studyTravel · Platform
Travel Ecosystem
Travel platform bringing flights, hotels, itineraries and loyalty together.
Next.jsNode.jsPostgreSQLStripe
Read the case studyLegal · SaaS
CO-LAW Group
Client intake, risk checks and document workflows for a boutique law firm.
Next.jsPostgreSQLAWSStripe
Read the case studyFAQs
Questions we get asked.
Straight answers on scope, cost, timelines and how we work. If yours is not here, ask us directly.
What does a C# and .NET development company do?
A C# and .NET development company plans, designs, builds, tests, deploys, and supports C# and .NET software. At Techsleight Labs, that can include discovery, architecture, UI/UX, API integration, QA, cloud deployment, analytics, and post-launch roadmap support.
Do you work with companies in the United Kingdom?
Yes. This C# and .NET development company page is focused on United Kingdom businesses. We support UK collaboration with clear written updates, weekly demos, and planned handoff points so distributed teams can move quickly.
How much does C# and .NET development cost?
C# and .NET development pricing depends on scope, integrations, user roles, design depth, compliance needs, and launch timeline. Discovery sprints start from £2,000, dedicated teams start from £9,500/month, and managed projects are quoted after scope validation.
Can you build a complete C# and .NET product, not just provide developers?
Yes. You can use Techsleight Labs as a full C# and .NET development company for strategy, design, engineering, QA, deployment, and support. You can also start with a small discovery sprint before committing to the full build.
Can you improve an existing C# and .NET application?
Yes. We often join existing C# and .NET products to fix performance, improve architecture, add features, stabilise releases, modernise UI, or prepare the system for scale. We begin with a focused audit so the first sprint is practical.
Who owns the code and product IP?
You own the code, documentation, product IP, design assets, and infrastructure setup created for your project. We can sign an NDA before discovery and work inside your repositories, cloud accounts, and project tools.
How fast can a C# and .NET development project start?
Discovery can usually begin within a few working days of the first call, and most projects start within 5–7 working days of sign-off. Larger builds usually need a short planning sprint to confirm scope, architecture, milestones, risks, and the right team before full development begins.
Do you provide post-launch C# and .NET support?
Yes. After launch, we can continue with monitoring, bug fixes, performance improvements, security updates, roadmap features, analytics, and handover support. Many clients keep a monthly retainer after the main release.
Start a project
Planning a C# and .NET project?
Tell us what you are building with C# and .NET. We will reply within one working day with questions, a first view on approach and the next step.
What happens next
- 1A senior engineer reads your brief within one working day, and replies with questions or a first view.
- 2A 30-minute call to understand the goal, constraints and what good looks like — no sales script.
- 3A written proposal with scope, milestones, team and a GBP estimate you can take to your board.
Techsleight Labs is a trading name of Krapton IT Consultancy.
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