A Coding Challenges section has been added to the Practicalli Clojure book http://practicalli.github.io/clojure/coding-challenges/ Covers 4Clojure, Exercism, CodeWars, ClojureScript koans and Advent of Code. These seem to be the most commonly used challenges websites. If you have any other suggestions, please let me know. I will be adding a selection of solution design journals for challenges from each of the websites over time and there are already links to code repository and YouTube playlists of solutions. Thank you