ASP.NET Core and modern .NET applications
We maintain and develop business applications built on ASP.NET Core and current .NET, and we build the modern .NET half of systems that are moving off .NET Framework while they stay in service.
Vendor support
- .NET 10
- Supported
- Security fixes
- Ends 14 November 2028
What you probably want to know first
- Can you support our existing application?
- Yes, provided you hold the source code or can obtain it. ASP.NET Core applications are usually the easiest systems to take over: the code builds with free tools, runs on Windows or Linux, and current .NET versions receive regular security fixes. The work is mostly getting the build, the releases and the dependencies back under control.
- Our application is on .NET 6 or .NET 8. Is that a problem?
- It is a planning date rather than a crisis. Each .NET version is supported for a fixed period, and moving from one modern version to the next is normally a small job compared with leaving .NET Framework. We check what the libraries you depend on need, move the application up, and run the tests before it goes live.
- What access do you need?
- Read access to the source code and, where possible, read-only access to the hosting environment and the database. Nothing changes on the live system while we look. A confidentiality agreement can be signed before anything is shared.
- What have you done with systems like this?
- OpenIRIS, the research-facility booking system we have supported since 2014, is moving from an ASP.NET MVC application to an ASP.NET Core API on .NET 10 one feature at a time, with old and new sharing the same database and sign-in. The OpenIRIS case study describes it.
Who this page is for
This page is for IT and operations managers whose business software is already built on ASP.NET Core and current .NET, or is part-way there, and who need someone to look after it and keep developing it. If your application is still on .NET Framework, the .NET Framework page covers the move.
Modern does not mean maintenance-free
An ASP.NET Core application built five years ago is not legacy in the way a VB6 system is, but it ages quickly if nobody looks after it. Each .NET release has a fixed support period. The packages it depends on publish security fixes that only help if someone applies them. The person who knew how to release it moves on, and the steps live in their head.
The work that keeps a modern .NET system healthy is unglamorous and regular: move to each long-term support release in good time, keep the packages current, keep the build and release automated, and watch the live system.
Systems that are part-way across
Many of the systems we see are half old and half new. A .NET Framework application has a newer ASP.NET Core API beside it, or a new module that talks to the same database. That is a sound way to modernise, provided both halves are maintained as one system: one sign-in, one database, one release process, and tests that check the old and new parts agree.
It is how OpenIRIS is moving: an ASP.NET Core API on .NET 10 is taking over from the original ASP.NET MVC application one feature at a time, with the two sharing a SQL Server database and the users’ sign-in, so the institutions using it see steady change rather than a switch-over.
What you get from us
A team that works in your repository, releases through an automated pipeline, keeps the system on supported versions and tells you plainly what each change will cost before it starts. For how support works day to day, see software maintenance.
Talk to us
Describe the system and what you need. You will hear back from someone who can answer technical questions.
Discuss your ASP.NET Core application 0800 433 7990What we do with ASP.NET Core systems
- Take it over
- We get the code building from a clean checkout, document how a change reaches production and make the release repeatable.
- Keep it on a supported .NET
- Each application is moved to the current long-term support release before its version stops receiving fixes, with the dependencies upgraded alongside it.
- Develop it
- New features, reports, integrations and APIs, built in small changes that are tested and released one at a time.
- Run old and new side by side
- Where part of the system is still on .NET Framework, the modern .NET application takes over one area at a time, sharing the database and the sign-in.
- Make it observable
- Structured logging, error tracking and performance monitoring, so problems are seen before users report them.
- Host it for less
- Modern .NET runs on Linux and in containers as well as on Windows, which often lowers hosting and licence costs.
How we take over an ASP.NET Core application
Build it
We build the solution from your repository and list every project, package and runtime version.
Find the release path
We work out how a change reaches production today, and put it into an automated pipeline if it is manual.
Check the dependencies
Every package is checked for known vulnerabilities and for support on the current .NET release.
Add a safety net
Tests around the main workflows, and monitoring on the live system, before larger changes start.
Agree the plan
Fixes, upgrades and development, in an order you agree, priced before each piece starts.
Support dates
Status is worked out against today's date each time this site is rebuilt. Dates come from the Microsoft .NET support policy; check there before relying on them.
| Version | Released | Security fixes end | Status today |
|---|---|---|---|
| .NET 10 | 11 November 2025 | 14 November 2028 | Supported |
| .NET 9 | 12 November 2024 | 10 November 2026 | Ending within a year |
| .NET 8 | 14 November 2023 | 10 November 2026 | Ending within a year |
| .NET 6 | 8 November 2021 | 12 November 2024 | Support ended |
A good fit when
- You have an ASP.NET Core application whose developer or supplier has gone.
- The application is on a .NET version that is out of support or close to it.
- You want to keep developing the system and need a team that can change it safely.
- Part of the system is still on .NET Framework and the rest has moved.
Probably not for you if
- The application is a product sold by a vendor who will not give you the source code; the vendor has to do the work.
Questions we are asked
How long is each version of .NET supported?
Long-term support releases, the even numbers such as .NET 8 and .NET 10, are supported for three years. Standard-term releases, the odd numbers, are supported for two years. The table on this page shows the current dates.
Is ASP.NET Core the same as ASP.NET MVC?
No. ASP.NET MVC 5 runs on .NET Framework, only on Windows, and is in maintenance. ASP.NET Core is its successor on modern .NET. The ideas are similar, so code and skills move across, but an MVC 5 application has to be migrated to run on ASP.NET Core.
Can you work alongside our own developers?
Yes. Some clients keep an in-house developer for day-to-day changes and use us for upgrades, larger pieces of work and cover. We work in your repository and follow your release process.
Tell us about your system
Say what it does, what it is built on and what is worrying you. We will reply with what we would look at first and whether we are the right people to help.