1. APNG Edit is a popular Firefox add-on for creating Animated PNG images. It can create animations by assembling individual (per-frame) images, or by running a user-created script to render each frame in a Canvas tag.

Pros: Easy to use, cross-platform.

Cons: Can’t open existing APNGs, no automatic frame difference optimization.

2. VirtualDub APNG Mod provides Animated PNG support for the popular video editing software VirtualDub. It can load and save APNG, with or without alpha channel. Automatic frame difference optimization helps to compress files more. VirtualDub filters provide a lot of processing options – crop, resize, etc.

Pros: Accepts all kind of input – video, image sequences, APNG/MNG files. Good compression.

Cons: Not cross-platform, Windows only.

3. APNG Anime Maker is another program to create animated PNG files. Provides flexible optimization options, including lossy with adjustable tolerance level, over selected image region.

4. Japng Editor is a Java library/editor to create APNGs from a sequence of individual images.

5. Animat is another Firefox add-on for creating APNGs.

Other tools:

gif2apng is a simple command-line GIF -> APNG converter.

APNG assembler 2.0 is an online PNG -> APNG app.