Revive Old Posts
This is an excellent plugin that will publish your WordPress content to various social media websites. The free version is limited to Facebook and Twitter -- but these both work flawlessly.
Share to Facebook, Twitter, LinkedIn, Google My Business
... Tumblr and also bring in your social networks from Buffer. Basically, all the most popular social networks are supported. Revive Old Posts allows you to share your content to multiple accounts on each of the supported social networks. No limitations.The propeller heads at Revive
So, lets dive in and install it, configure it and watch it share to Facebook and Twitter: