Background: In order to address the challenges in companies having no or limited effort datasets of their own, cross-company models have been a focus of interest for previous studies. Further, a particular domain of investigation has been Web projects. Aim: This study investigates to what extent effort predictions obtained using cross-company (CC) datasets are effective in relation to the predictions obtained using single-company (SC) datasets within the domain of web projects. Method: This study uses the Tukutuku database. We employed data on 125 projects from eight different companies and built cross and single-company models with stepwise linear regression (SWR) with and without relevancy filtering. We also benchmarked these models again...