About Secondant — who sits beside you

The story

Built for myself first.

I'm Jeroen Janssen. I've spent my working life in and around the built environment — with developers, investors and board members, the people who sign for what gets built. I write and speak about that world, and I see up close where the hours of the people at the top actually go.

Over the past years I built my own AI working practice. Not as an experiment, but as daily equipment: my documents, my analyses, my preparation, my digital brain — running on the same stack I now set up for clients. Secondant doesn't sell theory. It sells what I use every day.

Why this shape — one on one, eight clients at most? Because the work that matters can't be delegated. Your calculation, your memo, your knowledge. You don't build that in a classroom or with a licence. You build it with someone who sits beside you, knows your week, and makes one thing permanently faster every week.

Amsterdam · info@jeroen-janssen.com · jeroen-janssen.com

The name

Why secondant.

The secondant is the man in your corner in boxing. The second in a duel. And — the finest image — the second of a chess grandmaster: the one who prepares the openings, studies the opponent and works through the night, so the master wins the game.

Loyal, expert, discreet, and always in service of one person. That is the service. And the rook in the mark? A chess piece that is also a building. No such thing as coincidence.

What I believe

Four convictions.

AI is not an IT project

It's a personal working practice. You don't procure it, you build it — on your own work, in your own voice.

The person first, then the organisation

In construction and real estate, knowledge lives in people, not systems. Speed up the top and you speed up the firm.

Discretion is a product feature

No logos, no named cases. What happens at your table stays at your table.

Becoming redundant is the goal

A good second makes himself dispensable. After the engagement you can do it yourself — that's the deal.

Meet

Forty-five minutes.
On your working week.

Then you'll know exactly what a secondant gets you — or that it's not for you. Either is fine.

Book an intro call → info@jeroen-janssen.com