If you are looking for a ready-made solution (for a very large number of languages), you can try with Sketch Engine (go to Wordlist -> Keywords). [Disclaimer: I'm one of the developers]
see also this related question: https://www.researchgate.net/post/Does_anyone_know_a_good_on-line_terminology_extraction_software_for_FR_and_DE_Does_anyone_know_a_good_BILINGUAL_multi-word_term_extractor
i guess it late reply, this may help others wrote java library to extract the stopping and stemmer words from given link/file/text i guess that may help you.
demo link: https://exude.herokuapp.com/
source code of library git : https://github.com/uttesh/exude