Jacobus Johannes Pieter Oud, commonly called J. J. P. Oud was a Dutch architect. His fame began as a follower of the De Stijl movement.
Oud was born in Purmerend, the son of a tobacco and wine merchant. As a young architect, he was influenced by Berlage, and studied under Theodor Fischer in Munich for a time. He worked together with W.M. Dudok in Leiden, which is where he also met Theo van Doesburg and became involved with the movement De Stijl.
Between 1918 and 1933, Oud became Municipal Housing Architect for Rotterdam. During this period when many laborers were coming to the city, he mostly worked on socially progressive residential projects. This included projects in the areas of Spangen, Kiefhoek and the Witte Dorp. Oud was one of a number of Dutch architects who attempted to reconcile strict, rational, 'scientific' cost-effective construction technique against the psychological needs and aesthetic expectations of the users. His own answer was to practice 'poetic functionalism'.
In 1927, he was one of the fifteen architects who contributed to the influential modernist Weissenhof Estate exhibition.