unfiltered friend

That good friend with whom you can be your authentic and unedited self.

I’d much rather hang out with you, my unfiltered friend!

Unfiltered Friend

The friend who is unencumbered or reserved, completely open and honest with any personal information as well as personal preferences. They often demonstrate that by stepping over the line and providing Too Much Information.

After spending some time together on a car ride sarah went from being a friend to an unfiltered friend; I know too much about her.