NOTE: this review is of an old beta. Please see Mozilla Labs for a better description of the program and search addons.mozilla.org to find a more recent version.This APNG editor is a fully functional, easy to use, cross platform program for making animated PNGs. It is currently still a beta, but it does produce valid APNG files.

APNG Editor is a Firefox extension. APNG support will only ship with Firefox 3, for now you have to download the alpha version of Firefox.
Features
These are the features that are working in the beta version of the editor:

  • Load each frame from any PNG file
  • Set loop control (play forever, once, X times)
  • Optionally set the first frame (displayed in older browsers) to
    be hidden in newer browsers.
  • For each frame:
    • Set the offset of the frame from the top-left corner of the
      animation
    • Set the time to display
    • Set disposal options (clear image, keep image, revert frame)

Download
A beta version of APNG Editor (version 0.9) is available from here.

Installation
If you already have Firefox Alpha 5 or later, just click on the download link above, choose to open it with the Firefox Alpha if it doesn’t by default, and in the window that comes up click ‘Install Now’.

If you don’t have Alpha 5, here’s how to install it:

  • Go to this page
  • Click on the link for your operating system (Windows, OsX, or Linux)
  • Once the download is complete, install it as you would normally install Firefox.
  • Once installed, run it (on Windows the shortcut is called ‘Gran Paradiso’, not ‘Firefox’
  • Come back to this page using the Firefox Beta, and install the extension (see first paragraph of ‘Installation’, just above).
  • After the extension is installed, to start the editor open the Firefox Alpha, go to the ‘Tools’ menu and there should be an ‘APNG Editor’ there.

Note that Firefox Alpha is a development release and may corrupt your profile. I recommend that you create a new profile to keep your data safe while enjoying the new features of Firefox.