Like so many software companies that provide a free/open source version and also sell a "commercial" version, they make it as cryptic and unfriendly as possible to actually download and use the free one. Here is a typical example: https://mupdf.com/downloads/
There's two different files for download for Windows:
mupdf-1.18.0-windows.zip
mupdf-1.18.0-windows-tesseract.zip
What is "-tesseract"? No idea. I've looked all over that page, other pages, searched online, etc. No clue. Not as much as a single word explaining what the difference is or what "tesseract" means. Wikipedia's disambiguation page also lends no hint as to what it may refer to.
What is "tesseract"? And more importantly: what does it have to do with PDF viewing and why is it a separate file?