Artificial mutagenesis and chimeric/mosaic protein engineering have laid the foundation for antigenic characterization and universal vaccine design for influenza viruses. However, many methods used for influenza research and vaccine development require sequence editing and protein expression, limiting their applicability and the progress of related research to specialists. Rapid tools allowing even novice influenza researchers to properly analyze and visualize influenza protein sequences with accurate nomenclature are needed to expand the research field. To address this need, we developed Librator, a system for analyzing and designing protein sequences of influenza virus Hemagglutinin (HA) and Neuraminidase (NA). With the graphical user interface (GUI) and built-in sequence editing functions of Librator, biologists can easily analyze influenza sequences and phylogenies, automatically port sequences to visualize structures, then readily mutate target residues and design sequences for antigen probes and chimeric/mosaic proteins efficiently and accurately. This system provides optimized fragment design for Gibson Assembly of HA and NA expression constructs based on peptide conservation of all historical HA and NA sequences, ensuring fragments are reusable and compatible, allowing for significant reagent savings. Use of Librator will significantly facilitate influenza research and vaccine antigen design.