SWF () is an Adobe Flash file format used for multimedia, vector graphics and ActionScript. Originating with FutureWave Software, then transferred to Macromedia, and then coming under the control of Adobe, SWF files can contain animations or applets of varying degrees of interactivity and function. They may also occur in programs, commonly browser games, using ActionScript.

Programmers can generate SWF files from within several Adobe products, including Flash, Flash Builder (an IDE), Adobe Animate (the replacement for Adobe Flash as of Feb. 2016), and After Effects, as well as through MXMLC, a command-line application compiler which forms part of the freely-available Flex SDK. Although Adobe Illustrator can generate SWF format files through its "export" function, it cannot open or edit them. Other than using Adobe products, one can build SWFs with open-source Motion-Twin ActionScript 2 Compiler (MTASC), the open-source Ming library and the free-software suite SWFTools. Various other third-party programs can also produce files in this format, such as Multimedia Fusion 2, Captivate and SWiSH Max.

The term "SWF" has originated as an abbreviation for ShockWave Flash. This usage was changed to the backronym Small Web Format to eliminate confusion with a different technology, Shockwave, from which SWF derived. There is no official resolution to the initialism "SWF" by Adobe.