Scholars traditionally receive career credit for a paper based on where in the author list they appear, but position in an author list often carries little information about what the contribution of each researcher was. "Contributorship" refers to a movement to formally document the nature of each researcher's contribution to a project. We discuss the emerging CRediT standard for documenting contributions and describe a web-based app and R package called tenzing that is designed to facilitate its use. tenzing can make it easier for researchers on a project to plan and record their planned contributions and to document those contributions in a journal article.