Basically an Apple-specific reimplementation of Zstd: https://github.com/Cyan4973/zstd
Zstd & LZ4 being the work of single developer is amazing though.
But Jarek's ANS paper was first out in 2007, and almost no one paid attention to it, because it was plain inscrutable.
Many years later, it took an individual to create FSE (https://github.com/Cyan4973/FiniteStateEntropy), to prove that it could be transformed into something actually useful and competitive. Since then, the paper has been updated a few times, borrowing a few points from FSE in order to become more readable. But it's still very hard to read.
In contrast, FSE code can be copy/pasted.
And all of a sudden, lot of versions have popped out over Internet. By pure chance, they all look like derivatives of FSE or Fabian Giesen's rANS, but they pay tribute to Jarek's ANS paper, because quite clearly it is the source of their work, and prior existence of an actual open source implementation which works and looks pretty damn close to theirs was purely accidental.
This is not paying tribute where it's due.
"Admittedly, LZFSE does not aim to be the best or fastest algorithm out there. In fact, Apple states that LZ4 is faster than LZFSE while LZMA provides a higher compression ratio, albeit at the cost of being an order of magnitude slower than other options available in Apple SDKs. LZFSE is Apple’s suggested option when compression and speed are more or less equally important and you want reduce energy consumption."
https://developer.apple.com/library/ios/documentation/Perfor... has a section titled "Choice of Compression Algorithm"
Apple's libcompression also provides LZ4 if you need it: https://developer.apple.com/library/ios/documentation/Perfor...