I think I first heard about the Zstandard compression algorithm at a Mercurial developer sprint in 2015. At one end of a large table a few people were uttering expletives out of sheer excitement. At developer gatherings, that’s the universal signal for something is awesome. Long story short, a Facebook engineer shared a link to the RealTime Data Compression blog operated by Yann Collet (then known as the author of LZ4 – a compression algorithm known for its insane speeds) and people were completely nerding out over the excellent articles and the data within showing the beginnings of a new general purpose lossless compression algorithm named Zstandard. It promised better-than-deflate/zlib compression ratios and performance on both compression and decompression. This being a Mercurial meeting, many of us were intrigued because zlib is used by Mercurial for various functionality (including on-disk storage and compression over the wire protocol) and zlib operations frequently appear as performance hot spots.