the greatest american English corpus (>1B): https://www.english-corpora.org/coca/
biggest greek and latin root dictionary (??): http://www.macroevolution.net/root-word-dictionary.html
cambridge vocab profile for all CEFR levels (~?12k): https://englishprofile.org/american-english
cambridge dictionary (??): https://dictionary.cambridge.org/dictionary/english/
vocabulary/advantage (~2k words, ~?300 roots):
merriam-webster vocab builder (~1.2k words, ~250 roots): the anki version (~32k cards): https://ankiweb.net/shared/info/850055327
the anki guy: https://ankiweb.net/shared/info/995462426