The Ribosomal Database Project (RDP) provides researchers with aligned and annotated rRNA gene sequence data and tools for analyzing these sequences. The latest release, RDP 11.1, includes 2809,406 bacterial and archaeal small subunit (SSU) rRNA gene sequences and 62,860 fungal large subunit (LSU) rRNA gene sequences. The RDP tools, such as Classifier and Aligner, have been updated to accommodate the new fungal collection and high-throughput sequencing data. The RDP offers a variety of tools for browsing, searching, taxonomic classification, primer-probe testing, and tree building. The RDP Pipeline is designed for processing large volumes of amplicon sequence data, including single-stranded and paired-end reads. The RDP tools are available as open-source packages, allowing researchers to develop custom analysis pipelines. The RDP also provides interactive web interfaces and a workspace for researchers to upload and store their sequences. The RDP's mission includes user support through help pages, a wiki, and telephone assistance.The Ribosomal Database Project (RDP) provides researchers with aligned and annotated rRNA gene sequence data and tools for analyzing these sequences. The latest release, RDP 11.1, includes 2809,406 bacterial and archaeal small subunit (SSU) rRNA gene sequences and 62,860 fungal large subunit (LSU) rRNA gene sequences. The RDP tools, such as Classifier and Aligner, have been updated to accommodate the new fungal collection and high-throughput sequencing data. The RDP offers a variety of tools for browsing, searching, taxonomic classification, primer-probe testing, and tree building. The RDP Pipeline is designed for processing large volumes of amplicon sequence data, including single-stranded and paired-end reads. The RDP tools are available as open-source packages, allowing researchers to develop custom analysis pipelines. The RDP also provides interactive web interfaces and a workspace for researchers to upload and store their sequences. The RDP's mission includes user support through help pages, a wiki, and telephone assistance.