Small RNAs (sRNAs) are important biomolecules that exert vital functions in organismal health and disease, from viruses to plants, animals, and humans. Given the ever-increasing amounts of sRNA deep sequencing data in online repositories and their potential roles in disease therapy and diagnosis, it is important to enable federated sRNA expression querying across samples, organisms, tissues, cell types, and diseases. Here we present the sRNA Expression Atlas (SEA), a web application that allows for the search of known and novel small RNAs across ten organisms using standardized search terms and ontologies. SEA contains re-analyzed sRNA expression information for over 2000 published samples, including many disease datasets and over 700 novel, high-quality predicted miRNAs. We believe that SEA's simple interface and fast search in combination with its detailed interactive reports will enable researchers to better understand the potential function and diagnostic value of sRNAs across tissues, diseases, and organisms.