Willem joined Google in 2011 as a kernel developer. Before that, he built research operating systems in academia. At Cornell University he co-developed Nexus, a microkernel operating system that derives authorization from application invariants on confidentiality and integrity. At the Vrije University of Amsterdam he received his PhD for research on a high-throughput network stack and its application in intrusion detection. As Bachelor and Master student at Leiden University he implemented active and p2p networks.