The most caffeinated coffee, in THE ENTIRE WORLD, is now available in the United States, and can be delivered to your doorstep thanks to Amazon.
It's from South Africa and it has more than four times the caffeine of a regular cup. It's a relative newcomer, first made available in 2016, and is called Black Insomnia. It has 702 milligrams of caffine in each 12-oz cup, while a regular cup of coffee contains approx. 150 milligrams. BTW, the recommended daily dose of caffeine for an entire day is 400 milligrams. So yeah, you gotta be careful with this stuff.
If you dare - here's where you can order it.