There are many open source places hat will augment Arxiv, chemrxiv, bioRxiv SSRN but none will replace these pre-print website for immediate nonpeer reviewed research articles.
My favorite are
https://www.intechopen.com/
https://www.hindawi.com/journals/
https://www.mdpi.com/about/journals
https://www.omicsonline.org/open-access-journals-list.php
http://www.ijcse.net/