I have experience of building complex authentication systems like that in slack normal individual sign on and SSO using SAML 2.0. I have also used Oauth for facebook, twitter, google etc. login.
Relevant Skills and Experience
Jquery, AngularJS, NodeJs, ExpressJS, MongoDB, CouchDB, Neo4j, Redis, Memcache, Elastic Search, OAuth, Passport, Jwt etc.
Proposed Milestones
$100 USD - All requirements
Additional Services Offered
$1 USD - Will integrate one additional openID provider like google, twitter etc.