MozJPEG is a fork of libjpeg-turbo with 'jpgcrush' functionality built in.

This project's goal is to reduce the size of JPEG files without reducing quality
or compatibility with the vast majority of the world's deployed decoders.

The idea is to reduce transfer times for JPEGs on the Web, thus reducing page
load times.

'mozjpeg' is not intended to be a general JPEG library replacement. It makes
tradeoffs that are intended to benefit Web use cases and focuses solely on
improving encoding. It is best used as part of a Web encoding workflow. For a
general JPEG library (e.g. your system libjpeg), especially if you care about
decoding, we recommend graphics/libjpeg-turbo port.

WWW: https://github.com/mozilla/mozjpeg/