What key for Song?

LasTime

Lets say you're messing about with a fews notes that sound good together. Therefore there's a chance they might be in the same key. Is there any application online where by you can enter in certain notes, and it will show one or more keys that these notes are in. Obviously, the more notes you'd enter, the less possible keys there would. It would eventually narrow it down to two keys: the major key, and its relative minor.

Then having found the key, you could incorporate whatever little short few licks you came up with your into that key, and make them make sense, etc.