Almere and the Dutch government’s real estate development agency commissioned the plan from Mr. Maas, a passionate urbanist and designer of what he called “dense environments.” He worked with the former Almere alderman Adri Duivesteijn to get the project through bureaucratic hoops.

The bootstrap aspect of Oosterwold goes way beyond aesthetics: Energy, sewage and roads must also be figured out by residents, leading at least one person over the years to ask Mr. Maas, “Are you crazy?”

The HomeMaker software is intended to allay concerns. “We made it to calculate the ground price, the amount of water, the amount of solar cells needed,” Mr. Maas said. “It also figures out how to make a road — not only for the homeowner but for those who come after them.”

For the Dutch, the concept requires a new way of thinking.

“We have such a tradition of planning in the Netherlands,” said Michelle Provoost, an architectural historian and executive director of the International New Town Institute in Rotterdam. “New towns are always planned top-down, with no space for doing it yourself. So in that sense it’s groundbreaking.”

She acknowledged, “In some countries it wouldn’t be that experimental.”

What’s unusual, however, is the scale and density. When it’s completed, the plan is to have 15,000 homes and some 40,000 residents.

The Netherlands is the 32nd most densely populated country in the world, famous for harnessing nature with canals and windmills. Oosterwold’s master plan is driven by ecological concerns. New structures are only allowed to occupy up to a fourth of the land, and about half is devoted to agriculture, to bolster a sustainable ecosystem.