The following links (except opencup.org) are no long available. If you are looking for graphic user interfaces (GUIs) for running R. My advice is “Don’t”. One needs to learn to code one way or another.

If you insist on working with GUIs, then you would probably find R commander , Jamovi, RKWard,  Deducer, Blueskystatistics, and Rattle useful. GUI programs for R are often limited in their support for specialized R packages. Make sure the R packages you want are included in those GUI programs.

lme4

http://www.stat.ucla.edu/~jeroen/lme4.html

ggplot2

http://www.stat.ucla.edu/~jeroen/ggplot2.html

More

https://www.opencpu.org/apps.html