You've got aches and pains, perhaps a hodgepodge of symptoms. You just want to know what you might have and whether to self-treat, see your doctor, or (oh no) go to the ER. Symcat is a diagnostic tool to help you out.
The smart webapp walks you through what a medical professional might ask in a quick background check, from what your symptoms are and how long you've been experiencing them to how old you are and your gender and family history of diseases. Symcat then uses clinical data (aggregate patient health records) to predict what could be wrong and give you advice.
This isn't a great tool for hypochondriacs, of course and you shouldn't rely completely on online symptom checkers like these for all your health needs, but Symcat's intelligent diagnosis — the way it covers both symptoms and your background (anonymously, too) — makes it worth bookmarking. There's an Android app too.