I am the designer of Ishanekon: World Shapers, the (probably) biggest free indie TTRPG. With over 2,800 character options, I am pretty sure it is the game with the most options that is 100% free. But since I cannot prove it, I am stuck with the (probably) in the slogan for legal reasons.
So my questions are:
Do you know any free indie games that have more?
If not, do you have an idea how I could prove that IWS is indeed the biggest?
No, Pathfinder 2e does not count. It is definitely not indie, and it is technically not 100% free.
Edit: With character options, I mean Archetypes, Sub-Archetypes, Paths, Abilities, Talents, Traits, Items, and Item Upgrades. I do not mean different builds. Also, it is not a book. It is a website (https://world-shapers.com/). It has many filter options, including a beginner and core tag. So not all those options are part of the "core rulebook." Both tags reduce it significantly, making it more digestible for newcomers.