Keybase

Keybase is an open source data-encryption-themed command line program that hosts a directory of public social network keys and identify proofs. Developers can implement the Keybase API to access their directory programmatically. HTTP GET/POST requests can be sent with a JSON encoded structure to receive a given user's username, to calculate password hashes, and to login with a hash and csrf_token. The API can be embedded into clients or 3rd party applications, and all functionalities can also be utilized on Keybase.io's website and command line interface.