Files with the extension .APNG are animated PNG files (portable network graphics). .APNG files work in a similar fashion to animated GIF files but support 24-bit images and 8-bit transparency unsupported by the GIF format.

The .APNG format was created by Stuart Parmenter and Vladimir Vukicevic of the Mozilla Corporation.

The .PNG format consists of three main segments: image header, image data and image end. The .APNG format also contains data segments relating to: animation control, frame control and frame data.