Rooster, Resources of Organism Orthologs among Species Targeting Evolution Research, is designed for homologous gene identification, providing insights into the conservation and divergence of orthologous gene expression across species. These expression patterns offer crucial clues to understanding the molecular basis of phenotypic innovation and evolutionary adaptation. Rooster enables users to visualize the expression profiles of orthologous genes across more than 1000 species, facilitating comparative transcriptomic analysis. The platform incorporates precomputed one-to-one and one-to-many orthologous relationships between 1154 species and humans, allowing users to systematically explore gene evolution. This functionality is seamlessly integrated into the webserver, enabling both real-time querying and dataset downloads for further evolutionary studies.