ANI (file format)


The ANI file format is a graphics file format used for animated mouse cursors on the Microsoft Windows operating system.

Filename extension
Internet media typeapplication/x-navi-animation
Magic numberACON (4 bytes, ASCII)
Developed byMicrosoft
Type of formatanimated raster image format for mouse cursors

The format is based on the Microsoft Resource Interchange File Format, which is used as a container for storing the individual frames (which are standard Windows icons) of the animation.

File structureEdit

Animated cursors contain the following information: (in order of position in the file)

  • Name (optional)
  • Artist information (optional)
  • Default frame rate
  • Sequence information
  • Cursor hotspot
  • Individual frame(s), in ICO format
  • Individual frame rates (optional)

Frame rates are measured in jiffies, with one jiffy equal to 1/60 of a second, or 16.666 ms.


Sequence information present in the file determines the sequence of frames, and allows frames to be played more than once, or in a different order than that in which they appear in the file. For example, if the animation contains three different images numbered 1, 2 and 3, and the sequence is 1-2-3-2-1, (five frames) then only three icons need to be stored in the file, thereby saving storage space.

See alsoEdit

External linksEdit

  • Description of the ani file format
  • Vulnerability in Windows Animated Cursor Handling
  • .Ani Editor