Sign in with Tumblr #72
Description
Tumblr is still a thing, would be nice to allow logins with that.
TBD if it's actually reasonable to do though, because of the capricious nature of their profile URLs. According to the API docs, there is a permanent UID (which they incorrectly call a uuid) so the Twitter userID-in-fragment hack (e.g. username.tumblr.com#uid) could work.
There is an official client which should make this a lot easier, and looks very similar in usage to the Twitter client.