This will generate a custom dictionary for brotli and Zstandard compression (primarily for use with Compression Dictionary Transport HTTP compression).
Given a list of (up to 100) URLs it will download the contents of the URLs and use Brotli's dictionary_generator to generate a "raw" dictionary from the contents of the files. The raw dictionary is suitable for use with either Brotli or Zstandard compression.
It will also (optionally) test the effectiveness of dictionary-based compression for up to 20 of the URLs that you supplied. It does this by generating a new dictionary for each URL using only the other URLs (generating separate dictionaries for every page tested).
The URLs to be tested will be fetched anonymously (no cookies) using the User Agent string specified so they must be publicly available.
Please provide full URLs including the scheme (i.e. https://www.example.com/page1)