Its mode of action isn't identical to that of Adderall (amphetamine) and Ritalin (methylphenidate) but then again neither is that of caffeine, but it is still a stimulant. Adderall and Ritalin increase extra-cellular concentrations of dopamine and norepinephrine. Modafinil has been shown in many studies to elevate dopamine and norepinephrine concentrations in certain regions of the brain. It may not accomplish this as directly as Ritalin or Adderall, but the effect is there. There are additional glutamate-enhancing and GABA-reducing effects to Modafinil as well, which is perhaps where the "Modafinil is not a stimulant" misconception comes from. Still, administering a dopamine antagonist diminishes some of Modafinil's effects, much in the same way it diminishes the effects of Adderall or Ritalin.
But even without delving into the pharmacology of Modafinil, how you can you possibly not call Modafinil a stimulant? It promotes wakefulness, increases concentration, and substitutes for Adderall and Ritalin in narcolepsy treatment. It is also a Schedule IV controlled substance (FYI, do not attempt to import a controlled substance, but Adrafanil is a Modafinil precursor and is not scheduled.) indicating there is even a risk of abuse.