QPACK is the compression mechanism used by HTTP/3 to compress HTTP headers. It is in the process of being standardazed by the QUIC Working Group. The QPACK Internet-Draft is has been stable for some time and we don't expect functional changes to it before the final RFC is released. ls-qpack is a full-featured, tested, and fast QPACK library. The QPACK encoder produces excellent compression results based on an innovative mnemonic technique (to be described in a future article). It boasts the fastest Huffman encoder and decoder. The library is production quality. It is used in OpenLiteSpeed, LiteSpeed Web Server, and LiteSpeed Web ADC. WWW: https://github.com/litespeedtech/ls-qpack