Nederlands
Chaïm Zonnenberg

Chaïm Zonnenberg

Senior .NET Developer | AI Integration & Identity/SSO
De Bilt (Utrecht), Netherlands Born 1981 Available 2 days/week LinkedIn

Specialisations

AI Integration

Integrating AI into existing .NET applications. Chatbots, Semantic Kernel, prompt engineering. Multiple chatbots built.

Identity & SSO

OAuth2, OpenID Connect, SCIM, Azure Entra ID. Multiple secure token services built. IdentityServer4 migrations.

Backend & Architecture

C#, .NET, Azure, microservices. From design to production. 20+ years of experience in enterprise software.

Personal Skills
Entrepreneurship Project Management Lean/Agile Coaching Hands-on Mentality Self-taught Fast Learner Connector

What I've Built

  • Multiple secure token services built with IdentityServer4, OpenIddict and custom implementations
  • SCIM 2.0 provisioning endpoints for Azure Entra ID and Auth0, tested against enterprise tenants
  • IdentityServer4 migrations to Duende IdentityServer and OpenIddict
  • AI chatbots and Semantic Kernel integrations in existing .NET applications
  • Own SaaS products in production on Azure: Invullen.nl and Factuur-Assist.nl
  • Microservices architecture advised and guided at financial institutions
Sectors
Financial Services Government & Law Enforcement Real Estate Education & Assessment

Ventures

Software Assist
2018 – present

Freelance consultancy. Senior .NET development, AI integration and Identity/SSO solutions.

Invullen.nl
2025 – present

Survey platform. Built and launched independently.

Kingdom Assist
2022 – present

Digital solutions for Christian organisations. Practical tools for digital formats and church development.

Factuur Assist
2019 – present

Invoicing software. 135+ clients, built and managed independently.

Freelance Experience

Period Client Role
Sep 2018 – present Various clients Senior .NET Developer — AI integration, Identity/SSO (SCIM, OAuth2), backend development, architecture
Aug 2016 – Jul 2018 ABN AMRO Mortgages Team coach, software architect
Nov 2014 – Aug 2016 PFZW/PGGM Pension Management Architect
Oct 2013 – Sep 2014 Van Lanschot Bank Consultant
May 2012 – May 2013 ABN AMRO Mortgages Project Manager
Feb 2011 – Oct 2011 MyCom Team Lead

Employment

Period Employer Role
Mar 2009 – Jan 2011 Kadenza Valuation Models Expert
Aug 2006 – Feb 2009 DTZ Zadelhoff Real Estate Data Manager
Aug 2005 – Aug 2006 DTZ Zadelhoff Software Developer

Education

Degrees
MSc Computer Science

Utrecht University

2007
BSc Computer Science

Utrecht University

2006, cum laude
BSc Mathematics

Utrecht University

2006, cum laude
Additional Training
  • Samensturingsacademie — Successful Entrepreneurship and Change 2023
  • Microsoft — Data Science 2017
  • DTZ Zadelhoff — Real Estate and Brokerage Traineeship 2006 – 2007

Tech Stack

AI
Claude Code Semantic Kernel OpenAI Azure AI Foundry
Identity
OAuth2 OpenID Connect Azure Entra ID SCIM IdentityServer4 OpenIddict
.NET & Cloud
.NET 10 C# Azure Docker Kubernetes (AKS) SQL Server
Frontend
Vue 2/3 Angular TypeScript
DevOps
Azure DevOps CI/CD Playwright

Interested?

Get in touch for an introductory meeting or more information.

Get in touch