Ocean Gene Atlas(OGA) is a webservice to explore the biogeography of marine genes based on sequence similarity with environmental genomics datasets. OGA is currently implemented with the Tara Ocean Microbiome-Reference Gene Catalog database and the Marine Atlas of Tara Ocean Unigenes. Gene abundance estimates are computed for DNA metagenomes from the smallest Tara Oceans size fractions (from 0 to 3 µm, OM-RGC), and for RNA metatranscriptomes from Tara Oceans larger size fractions (0.8 to 2000µm, MATOU). OGA also includes curated Tara Oceans Eukaryotic Metagenome and Single-Cell Assembled Genomes (MAGs and SAGs), metagenomics-based transcriptomes (MGTs) and metagenome-assembled bacterial and archaeal genomes from the polar Arctic Ocean (Arctic MAG+G).