The following list of plugins have all been tested on sites I’ve created or on my own. So they worked for me but I cannot guarantee they will work 100% on your own WordPress website. Remember to test before using on a dev or local site before a live website.
I don’t list all plugins I’ve tested or used, only the ones I use a few times or are too good not to be listed.
Last update: 2015
Active installs: 50 000+
Tested August 2017
Verdict: Even though its an old plugin that seems to have no support, it does an excellent job of allowing syntax code to be added to a post or page.