Adobe Fireworks

Adobe Fireworks is an image editing program, originally developed by Macromedia, later bought by [https://en.wikipedia.org/wiki/Adobe_Inc. Adobe]. It is significant for also being used as an animation program, in order to create some of the GIF-based sprite animations present on the web.

Usage of PNG as a project file format
Interestingly, instead of having its own file format for maintaining editable versions of projects (like Flash's ), Fireworks made use of   for this purpose, filling such files with its own chunk types.