Smartersoft

Why this conversation

Every school has a timetable, and every teacher has a calendar on their phone. Stephan van Rooij built the bridge between the two, starting at university. The host recorded with him at Techorama Netherlands 2026 in Utrecht on 27 October 2026, where they talked about a service that grew into his full-time job, how it scales, and why he now spends so much time on security.

School schedules in every calendar

“In university, I accidentally started my own company”, Stephan said. What it does is take school schedules and put them in everybody’s digital calendar: “math Wednesday from 9 to 10, English from 10 to 11”. Each person’s own schedule, in their personal calendar.

“It is growing fast. We have so many customers, so many teachers that are being helped with this software”, and for a few years it has been his full-time job. He counts around 200 schools, from schools with 100 teachers to schools with 2,000 and everything in between: “a multitude of many thousands of teachers that are helped by my software”. Roughly half a million users, the host suggested: “You could say that, yes.”

Scaling with queues on Azure

How does he manage that scale? “It is all built using message queues, events.” Changes to a schedule come in and are picked up by the queuing system, which makes the changes in separate queues, each processed separately. If the number of messages in a queue goes up, more Docker containers start automatically, and the count goes back to zero when the work is done. Behind it are Azure Functions and Service Bus. The host summed it up: everything managed by Azure Functions, “so it’s super scalable”. “Yes, exactly.”

To come on board, a school makes a contract. The website is roostersync.nl, “the Dutch for Schedule Sync”. A school can make an appointment, and the team arranges and configures everything, “and then they are in the system.”

Security, more than ever

Next to that, Stephan does a lot about security: “Security is more important than ever. You cannot imagine how important security is.” His team is putting a very big effort into more security, and he tries to convince other developers to do more in their own applications: how to test role-based access control, and how to test automatically that an application will not go live with endpoints that do not require authentication. “And that is how they made me a Microsoft MVP in security”, he said, because they like him telling the community about it.

Speaking at more conferences

For the future, he sees himself speaking at more conferences, because security is going to matter more than ever, “with AI figuring out leaks you didn’t even know existed”. “I see me giving more talks about this and helping others make their software more secure.”

Where to find Stephan

He is on LinkedIn as Stephan van Rooij, and “I also have a blog where I post various articles on security and home automation stuff.”

When it comes out

The episode is edited and in the release order. Like every episode it goes out on YouTube first, then on Apple Podcasts, Spotify and Amazon Music.