Employees generate a rich source of information by publishing employer reviews online. However, researchers seeking to harness employer review data face an elusive body of research to build on. Therefore, I present a systematic, multidisciplinary literature review, presenting the information obtained from employer reviews, the research topics covered, and the data sources used. My analysis of 28 peerreviewed journal articles shows that studies extract insider knowledge, information on employee satisfaction and changes in employee satisfaction, insights into workplace culture, and linguistic style from employer reviews. Studies do so to predict firm performance, to explore employee satisfaction factors, and to uncover the linguistic style of employer reviews. Glassdoor is the primary data source used. Finally, I identify five avenues for further research.