I'm an independent .NET consultant and trainer based in Göteborg, Sweden, working with clients across Europe through my company TN-Data.
- Microsoft .NET MVP
- Professional trainer with 16+ years of experience
- Course author on Dometrain
- Conference speaker
- Consultant specializing in .NET, software architecture, and web security
Popular blog posts
- Introducing the Cloud Debugger for Azure
- Improving ASP.NET Core security by putting your cookies on a diet
- How I built my own Sega Mega Drive hardware dev kit from scratch
Open source
- Cloud Debugger for Azure: a teaching and exploration tool for Azure cloud developers.
- Coding Agent Explorer: a real-time .NET proxy and dashboard for inspecting AI coding agent API calls.
- Edument CQRS and Intentful Testing Starter Kit: a C# CQRS framework for event-sourcing projects.
- TN-Validate: a C# fluent validation library.
- C# School (ebook): co-authored, free 300+ page guide covering C# foundations.
Professional timeline
- 1996–1997
- Compiled and published the Programmers Heaven CD-ROMs (two volumes) containing 12,000+ source codes, tutorials, components, and tools, distributed worldwide.
- 1996–2008
- Created Programmers Heaven, an online developer community that reached 750,000+ monthly visitors at its peak.
- 2003–2008
- Built and ran CodePedia, a developer wiki platform.
- 2006
- Co-authored the C# School ebook.
- 2008–2010
- Independent .NET consultant implementing online marketing systems.
- 2010–2021
- Co-founded Edument and Edument Training, a .NET consulting and training company that grew to around 35 employees and five offices across Sweden and Prague.
- 2010–2013
- Primary organizer of Community Day, a one-day conference held in Malmö, Göteborg, and Stockholm with local and international speakers.
- 2013
- Co-created the cqrs.nu website, a free community reference covering the Command Query Responsibility Segregation (CQRS) pattern with guides, a C# starter kit, and the intentful testing approach.
- 2021–present
- Independent consulting and training again, focused on .NET, architecture, and security.
- 2025
- Awarded the Microsoft .NET MVP title, recognizing community contributions to the .NET ecosystem.
Personal history
The beginning
My computing journey started with a Commodore VIC-20 in 1981. At age 11 I enrolled in evening programming classes. That same year I was featured in a local newspaper after demonstrating my skills at a local computer exhibition.
Atari ST demo scene
With friends I co-founded the Atari ST demo group Sync. We released a number of demos and applications. I co-authored Audio Sculpture, a sound-tracker music application for the Atari ST written entirely in 68K assembly, which was distributed across Europe.
Sega Mega Drive reverse engineering
Without official documentation or development hardware, I reverse-engineered the Sega Mega Drive and built a custom dev kit that connected to my Atari ST. I wrote up the full story, including the hardware design, in this blog post.
Programmers Heaven CD-ROMs
Around 1996, I compiled and published two Programmers Heaven CD-ROMs filled with source code, tools, tutorials, and articles that I had collected over the years. They were sold and distributed worldwide through retail channels.
Programmers Heaven website
I launched Programmers Heaven in 1996 as an online community for developers; it grew to 750,000+ monthly visitors at its peak. Running it gave me extensive experience with large-scale web operations.
Video Course Author
I have a recorded course on Dometrain, a 12-hour deep dive into authentication and authorization in ASP.NET Core, covering both foundations and practical implementation.
What to do next?
Want to know more? Explore:
- My training offerings at tn-data.se/training
- My consulting services at tn-data.se/consulting
- My blog posts at nestenius.se
Have a project in mind or looking for training for your team? I'm always happy to have a conversation. Reach me via the contact page or at tn-data.se.