nQuant is a C# color quantizer producing high quality 256 color 8 bit PNG images using an algorithm optimized for the highest quality possible.
Zstandard, or zstd as short version, is a fast lossless compression algorithm, targeting real-time compression, providing high compression ratios. It offers a very wide range of compression / speed trade-off and is deployed within Facebook
Tools for using Zstd : 7-Zip with support Zstd - Zstd plugin for 7-Zip
.Net Wrapper for Zstd : ZstdNet - Zstandard.Net