The Omics Discovery Index (OmicsDI) provides dataset discovery across a heterogeneous, distributed group of Transcriptomics, Genomics, Proteomics and Metabolomics data resources, including both open and controlled access data resources. The resource provides a short description of every dataset, including accession, description, sample/data protocols biological evidences, and publication. Based on these metadata, OmicsDI provides extensive search capabilities, as well as identification of related datasets by metadata and data content where possible. In particular, OmicsDI identifies groups of related, multi-omics datasets across repositories by shared identifiers.