FLB is the extension given to files that are created by a relational database management system called FileMaker Pro. FLB files are used to store labels used in the program. This design is then used to fill it with records from the database and is most often printed. It can be, for example, a database of addressees printed on labels attached to envelopes.

FileMaker Pro is a Windows and MAC-based tool, and FLB files are generated using the XML format.