This caffeine addiction diagnosis tool can give you a good idea just how addicted to caffeine you really are.
While there is still ongoing debate as to how caffeine should be classified substance wise, anyone that has ever tried to quit caffeine can attest that the withdrawal symptoms can be quite uncomfortable.
So, in some sense, caffeine is definitely addictive. At any rate, caffeine is the most used psychoactive substance on the planet, therefore, it must have at least some grip on the billions of people who consume caffeine daily.