File extension
.swf
SWF File Format Specification
.swf files are Flash (Small Web Format) movies: a compact vector-based format for animation, interactivity, and ActionScript applications that dominated early interactive web content and is now retired.
Known meanings
Formats and reference material for .swf
SWF File Format Specification
SWF File Format Specification
Macromedia Flash File Format (SWF)
Macromedia Flash File Format (SWF)
Details
Format notes
SWF (Flash)
SWF (officially “Small Web Format,” long read as “Shockwave Flash”) was the delivery format of Adobe/Macromedia Flash. It was designed to package vector graphics, animation, embedded raster images and audio/video, and interactive behavior driven by the ActionScript language into a compact file that a browser plug-in could play. For roughly two decades SWF was the dominant format for web animation, games, rich advertisements, and interactive applications.
An SWF file begins with a signature — FWS for uncompressed, or CWS (zlib) and
ZWS (LZMA) for the compressed variants — followed by a header with the frame size,
rate, and count, and then a series of tagged records defining shapes, sprites,
timelines, scripts, and embedded media. The vector-based design let content scale
smoothly, and the scripting engine made SWF effectively an application platform, not
just an animation format.
Retirement And Preservation Notes
Adobe ended support for Flash Player at the end of 2020, and browsers removed the plug-in, so SWF is now a legacy/retired format that no longer plays in mainstream environments. Preservation efforts rely on emulators and open players (such as the Ruffle project) and on documentation of the format. Where possible, migrating important content to modern web technologies (HTML5, canvas/WebGL, video) is the path forward.
Security Notes
The Flash Player was a frequent target of exploits, and SWF files can contain scripted behavior and embedded media, so untrusted SWF should be treated as active content and only ever run inside a sandboxed, modern player rather than a legacy plug-in.
Further Reading
- Ruffle (open-source Flash emulator):
https://ruffle.rs/