Portable Network Graphics

Portable Network Graphics (PNG, officially pronounced , colloquially pronounced ) is a raster-graphics file format that supports lossless data compression. PNG was developed as an improved, non-patented replacement for Graphics Interchange Format (GIF).

Animated Portable Network Graphics (APNG) is a file format which extends the Portable Network Graphics (PNG) specification to permit animated images that work similarly to animated GIF files, while supporting images with a higher color depth and full alpha transparency not available for GIFs. It also retains backward compatibility with non-animated PNG files. It was developed by the Mozilla Foundation in 2004.

file format

file format

Zopfli is a data compression library that performs deflate, gzip and zlib data encoding. It achieves higher compression ratios than mainstream Deflate and zlib implementations at the cost of being slower. Google first released Zopfli in February 2013 under the terms of Apache License 2.0. Google archived the project in October 2025.