Brotli added custom dictionaries in 2014 or 2015 (before zstd format was even frozen). We are currently working on a new more efficient custom dictionary that u

Brotli added custom dictionaries in 2014 or 2015 (before zstd format was even frozen). We are currently working on a new more efficient custom dictionary that uses context and transforms to ramp up the impact of the custom dictionary (by about 20%).