Abstract: The regularized Poincare' integral operators are a new tool in the analysis of differential forms that have a variety of different applications. In particular, they allow the construction of vector and scalar potentials of optimal regularity in terms of fractional order Sobolev norms. They also have useful mapping properties in polynomial spaces that are related to discrete differential forms. One recent application is the completion of the proof of the discrete compactness of the p version of edge elements approximation of the Maxwell eigenvalue problem. In the talk, these integral operators and their companions, the Bogovskii integral operators, are presented with their main properties. Their role for the p version edge element approximation of the Maxwell eigenproblem is explained.