"We offer a free, monthly renewable plan! This plan lets you wake up 5 URLs every 30 minutes. At the end of the month, we send you a mail with a link to renew your free plan. As easy as could be!" now all I need is a free service to check my email and click the renew link once a month :)

That's fair. There are probably easier ways, but I like the added benefit of having access to performance metrics for free if I need them.