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I believe a new site on category theory just came online. Kerodan.net "an online resource for homotopy-coherent mathematics".
Kerodon is an online textbook on categorical homotopy theory and related mathematics. It currently consists of a handful of chapters, but should grow (slowly) over time. It is modeled on the Stacks project, and is maintained by Jacob Lurie.
Link's broken, here's a working on https://kerodon.net/changes
As you can see, it's not actually particularly new. It's quite nice though.
What a cute mascot!
It makes the homepage look like a math book for children and then .... "Chapter 1: The language of -categories".
The world would be a better place if there were more math books like that :smile:
This is Luries HTT in webpage form. Though I think there are a number of new things and different presentations