hangups is the first third-party instant messaging client for Google Hangouts. It includes both a Python library and a reference client with a text-based user interface.
Unlike its predecessor Google Talk, Hangouts uses a proprietary, non-interoperable protocol. hangups is implemented by reverse-engineering this protocol, which allows it to support features like group messaging that aren’t available in clients that connect via XMPP.
hangups is still in an early stage of development. The reference client is usable for basic chatting, but the API is undocumented and subject to change. Bug reports and pull requests are welcome!