Countless times I’ve heard people refer to their website as a “platform”. But it rarely is. Does it provide the ability for others to deploy or create new applications? Do you expose your data or functionality through a public API? If yes, only then you may call your website a platform. Facebook used to be just a website, now it also has the “facebook platform”, because it allows others to leverage its data and functionality through a set of APIs and the ability to deploy applications to it.
But “website” sounds like those html-only static pages that are not cool, and you don’t want your product to sound uncool? Here’s a suggestion – use “product” or “service”. Your site most likely offers some service to its users, so it’s an “online service”. But drop “platform” from your vocabulary until you really have a platform.