Concern over the mandatory two-year armed forces conscription in South Africa led the family to emigrate to Calgary, Alberta, Canada in November 1977.

In 1993, de Raadt founded NetBSD with Chris Demetriou, Adam Glass, and Charles Hannum, who felt frustrated at the poor quality of 386BSD and believed an open development model would be better.

The new project focused on clean, portable, correct code, with the goal of producing a unified, multi-platform, production-quality BSD operating system.

De Raadt played a vital role in the creation of the SPARC port, implementing much of the initial code together with Chuck Cranor.

[3] In December 1994, de Raadt was forced to resign from the NetBSD core team, and his access to the source repository was revoked.

[4] In his book Free for All, Peter Wayner claims that De Raadt "began to rub some people the wrong way" before the split from NetBSD,[5] while Linus Torvalds has described him as "difficult".

In particular, De Raadt has worked to convince wireless hardware vendors to allow the firmware images of their products to be freely redistributed.

De Raadt has commented that "most Taiwanese vendors give us documentation almost immediately," allowing open source drivers to reliably support devices, as opposed to the lack of willingness from US companies like Intel and Broadcom to release firmware images free from licensing restrictions.

You've told the entire BSD community who may want to use a driver for this chip later, that because of a few GPL issues you are willing to use very strong words—published very widely—to disrupt the efforts of one guy who is trying to do things for them.

They will see your widely posted mail as an overly strong position.Another clash occurred in August 2007, when a group of Linux developers attempted to modify the license of dual-licensed ath5k driver.

De Raadt summarised the issue as follows:[16] GPL fans said the great problem we would face is that companies would take our BSD code, modify it, and not give back.