The CGView Server is a comparative genomics tool designed for visualizing circular genomes, including bacterial, plasmid, mitochondrial, and chloroplast genomes. It generates graphical maps that display sequence features, base composition plots, analysis results, and sequence similarity plots. The server accepts various sequence formats, including raw, FASTA, GenBank, and EMBL, and allows the inclusion of additional feature information via GFF files. It uses BLAST to compare the primary sequence to up to three comparison genomes or sequence sets, and the results are converted into graphical maps. The server offers options to control which features are displayed and how they are drawn. It can be used to visualize features associated with any of these genome types and aid in identifying conserved genome segments, horizontal gene transfer instances, and differences in gene copy number. The server can also visualize regions of a known genome covered by newly obtained sequence reads. The CGView Server can be accessed at http://stothard.afns.ualberta.ca/cgview_server/. It integrates several sequence analysis procedures and tools with the CGView genome visualization program. The server accepts a variety of commonly used data formats and generates high-quality, fully labeled graphical maps. While the server returns static images, it includes an option for generating zoomed maps. It may not generate conventional linear maps, but the web-based Microbial Genome Viewer can be used for this purpose. Despite these limitations, the CGView Server can aid in the identification of conserved or diverged genome segments, instances of horizontal gene transfer, and differences in gene copy number. Sample maps and data sets are available at the server's website.The CGView Server is a comparative genomics tool designed for visualizing circular genomes, including bacterial, plasmid, mitochondrial, and chloroplast genomes. It generates graphical maps that display sequence features, base composition plots, analysis results, and sequence similarity plots. The server accepts various sequence formats, including raw, FASTA, GenBank, and EMBL, and allows the inclusion of additional feature information via GFF files. It uses BLAST to compare the primary sequence to up to three comparison genomes or sequence sets, and the results are converted into graphical maps. The server offers options to control which features are displayed and how they are drawn. It can be used to visualize features associated with any of these genome types and aid in identifying conserved genome segments, horizontal gene transfer instances, and differences in gene copy number. The server can also visualize regions of a known genome covered by newly obtained sequence reads. The CGView Server can be accessed at http://stothard.afns.ualberta.ca/cgview_server/. It integrates several sequence analysis procedures and tools with the CGView genome visualization program. The server accepts a variety of commonly used data formats and generates high-quality, fully labeled graphical maps. While the server returns static images, it includes an option for generating zoomed maps. It may not generate conventional linear maps, but the web-based Microbial Genome Viewer can be used for this purpose. Despite these limitations, the CGView Server can aid in the identification of conserved or diverged genome segments, instances of horizontal gene transfer, and differences in gene copy number. Sample maps and data sets are available at the server's website.