CRISPOR.org is a web tool designed to assist in CRISPR/Cas9 genome editing experiments. It identifies and ranks guide RNAs based on their potential off-target effects and on-target activity, providing comprehensive support from selection to validation. The tool has expanded its genome coverage to over 150 genomes and includes features such as batch design for genome-wide CRISPR screens, custom oligonucleotide design for cloning, and next-generation sequencing primer design for off-target mutation testing. CRISPOR also offers interactive visualization through the UCSC Genome Browser and tools for off-target primer design and gene knock-out screens. Recent developments include support for non-spCas9 nucleases, genomic variant filtering, and increased flexibility in basic features. The tool is available at http://crispor.org, with the full source code and a standalone command-line version available on GitHub. Future plans include support for base editors and improved DNA donor design tools.CRISPOR.org is a web tool designed to assist in CRISPR/Cas9 genome editing experiments. It identifies and ranks guide RNAs based on their potential off-target effects and on-target activity, providing comprehensive support from selection to validation. The tool has expanded its genome coverage to over 150 genomes and includes features such as batch design for genome-wide CRISPR screens, custom oligonucleotide design for cloning, and next-generation sequencing primer design for off-target mutation testing. CRISPOR also offers interactive visualization through the UCSC Genome Browser and tools for off-target primer design and gene knock-out screens. Recent developments include support for non-spCas9 nucleases, genomic variant filtering, and increased flexibility in basic features. The tool is available at http://crispor.org, with the full source code and a standalone command-line version available on GitHub. Future plans include support for base editors and improved DNA donor design tools.