FSA is an extension given to files that have been generated by specialized equipment for analyzing deoxyribonucleic acid (DNA) particles. FSA files are used to store data obtained during the analysis of research material using a DNA sequencer. FSA is a text file in FASTA format that stores nucleic acid and protein sequences. Such a file can be opened in any editor. It is allowed to add descriptions and comments to the file by the user.

FSA files are not commonly found and are mainly used in bioinformatics.