Github: I use Github to backup all my R codes and collaborate with others. As soon as I make a change to my code, I push it to Github to make sure that I can go back to that version of my code later if I need to. Github also makes it easy to see what are the differences between two versions of the code and keep track of issues to fix in the code. Github is easy to use in conjunction with RStudio since RStudio provides a menu for pushing code to Github. For researchers, Github provides unlimited private repositories for free (https://help.github.com/en/articles/applying-for-an-educator-or-research...).
Zotero: I use Zotero to keep articles I read organized by project. By downloading the Zotero plugin for Chrome, I can download articles and save all their meta-data (authors, title, etc.) using one click of a button. Citations can then easily be exported to Bibtex when writing a paper. By default, Zotero syncs to the Cloud but you only get limited free storage that way. Instead, in the settings, syncing can be disabled which allows to save an unlimited number of articles. In addition, by changing the folder where articles are saved in Settings to a e.g. a OneDrive folder, articles are backed up to the Cloud and accessible from other platforms.