Welcome to athisomiRdb, a comprehensive database dedicated to isomiRs of Arabidopsis thaliana. Our database houses an extensive collection of isomiRs derived from miRBase annotated miRNAs of Arabidopsis thaliana. These isomiRs have been curated from 2,757 miRNA-seq samples obtained from the Sequence Read Archive (SRA), ensuring a robust and reliable dataset. With our consistent and stringent criteria, we have compiled over 20,764 distinct miRNA isoforms, all originating from the miRBase (release 22.1) annotations of Arabidopsis thaliana miRNAs. Our database provides a valuable resource for researchers and scientists interested in exploring the diversity and expression patterns of isomiRs in Arabidopsis thaliana.