Nonmarine ostracods, tiny crustaceans with an excellent fossil record, are common in aquatic ecosystems. The Ostracod Metadatabase of Environmental and Geographical Attributes (OMEGA) facilitates access to global geographical and environmental distributional data for nonmarine ostracods, supporting applications in biodiversity auditing, biogeography and the calibration of species as fossil proxies for past environmental and climatic change. Citizen Scientists can help improve accuracy and coverage of datasets by adding, correcting and validating the geographical coordinates of localities.