Available for new assignments from September 2026
Experience
I have been building software in .NET since 2007; since 2015 as an independent contractor under the name Mark Smit .NET. The constant throughout all assignments: modernising existing systems and teams from within — from WebForms to MVC, from SVN to Git, from fortnightly releases to CI/CD, and now from no AI to AI.
M.Sc. Computer Science (TU Delft) · Microsoft certification Programming in C# (70-483) · Also: .NET performance analysis and improvement as a consultancy offering.
Previously worked for, among others
Timeline
- 2024 – present
Sabbatical — AI deep-dive & own build project
Deep-dive into how LLMs and BERT work and are (post-)trained, and into applying them: triage, categorisation, summarisation, data extraction and creating relations. Built: a personal knowledge and productivity system with vector search, local Whisper transcription, structured-output extraction and BERT classification.
- 2016 – 2024
T-Mobile Netherlands (later Odido) — developer → team lead
Eight years on the order-fulfilment system, from growth phase to maturity. Major refactoring efforts resulting in an extensive automated test suite; introduced CI/CD: from fortnightly-only deploys to being able to release at any moment. During the team's growth from 6 to 20 developers I held the technical lead over the recruitment process; later team lead of the order-fulfilment team.
- 2016 (Jun – Dec)
Vodafone Thuis — .NET developer
Built LookingGlass, a troubleshooting app for second-line agents that is still in use today — set up as a stand-alone MVC app to demonstrate the advantages over WebForms, after which a migration programme for the entire system followed. Also set up and carried out the migration from SVN to Git.
- 2016 (May – Jun)
CBG — WieWasWie.nl
Further development of the largest genealogy site in the Netherlands.
- 2016 (Jan – Apr)
Funda — backend developer
Homepage and search results of the largest housing site in the Netherlands, in a mature Scrum team with one of the best CI/CD pipelines in the country: dozens of fully automated deploys every day. I took that knowledge with me to Vodafone and T-Mobile.
- 2015 (Oct – Dec)
Axendo — Sitecore & Umbraco
Including IAmsterdam.com (Sitecore) and the Dutch broadcaster EO's website (Umbraco).
- 2011 – 2015
uWebshop — open source e-commerce for Umbraco
Packaged product on top of the open source CMS Umbraco; full-time for most of 2012, maintenance afterwards. Visible at github.com/uWebshop.
- 2008 – 2015
Mindbus — medior → senior .NET web developer, team lead, Scrum master
All aspects of software development: client contact, requirements, architecture, development, testing, deployment and process improvement. Highlight: CvI-net, a complex application and assessment system (over 1,000 data fields, hundreds of thousands of pupils) with a flexible schema that end users could extend themselves — an early example of meta-model thinking that directly relates to today's schemas for structured LLM output.
- 2007
Start: game development in C#
Internship at Cannibal Game Studios (game engine, C#/XNA) and a freelance serious game for the Dutch Heart Foundation (Hartstichting).
In short
18+ years of .NET
C#, architecture and web development in enterprise environments — telecom, platforms, government-related.
Technical leadership
Team lead and Scrum master; technical lead for recruitment during growth from 6 to 20 developers.
Proven modernisation
MVC, Git and CI/CD transformations in production environments that couldn't afford to stand still.
Up-to-date AI knowledge
LLMs, RAG, structured output and classification — deepened during the sabbatical and in daily use.