I haven't done any chemical analysis on the purity of the caffeine that I bought but compared to the caffeine powder I was using before it feels just as strong if not a little stronger than what I had. PLEASE BE CAREFUL WHEN WORKING WITH THIS, TOO MUCH CAFFEINE CAN KILL YOU!! I use a tiny measuring spoon to measure out "a smidgen" (that's what it's called) which equates to ~75mg-100mg of caffeine (which is about a cup of coffee's worth). I've been using it for a couple weeks now, the consistency is actually better than what I had before which is great because it dissolves in my morning beverage quicker :) WAY more affordable that buying a cup of coffee everyday!
Just be sure not to use too much. A tiny bit on the tip of a butter knife is plenty. And, keep in mind that this is bitter. If you mix it in with your protein smoothie it's hardly noticeable.