With increasing use of genomic sequencing technology, phylogenetic studies routinely require manipulating and summarizing thousands of alignments. Currently available software for these tasks uses considerable computing resources and are designed for users with substantial knowledge of command line applications. We develop SEGUL, a compiled, single-executable tool for fast alignment manipulation and summary tasks. SEGUL runs native on Windows, Linux, and macOS, includes native support for Apple ARM Macs, and offers fast execution times and low memory footprints regardless of dataset size, operating system, and CPU architecture (i.e., ARM or x86_64 CPUs). SEGUL includes a user-friendly command line interface, safety features, and extensive documentation to aid beginners, while also providing advanced features. Keywords: segul, alignment manipulation, concatenation, phylogenomics, phylogenetics, bioinformatics