ORSON combine state-of-the-art tools for annotation processes within a Nextflow pipeline: sequence similarity search (PLAST, BLAST or Diamond), functional annotation retrieval (BeeDeeM) and functional prediction (InterProScan). When required, BUSCO completness evaluation and eggNOG Orthogroup annotation can be activated. While ORSON results can be analyzed through the command-line, it also offers the possibility to be compatible with BlastViewer or Blast2GO graphical tools.