Blaine Cook (born 19 December 1980) is a Canadian software engineer, now living and working in London, UK. He is the principal co-author of the OAuth and Webfinger specifications. He is the former lead developer of social networking site Twitter. He has also worked for Yahoo! on the Fire Eagle project and for BT Group as part of their Open Source Osmosoft team. He is now a founder of collaborative text editing startup Poetica.