gologin is a Go library that provides chainable HTTP handlers for OAuth1 and OAuth2 authentication flows, supporting providers like Google, GitHub, Twitter, Facebook, Bitbucket, and Tumblr. It implements the full OAuth authorization code flow with CSRF protection via state cookies (OAuth2) and temporary credential persistence (OAuth1). The library is built on Go's standard `http.Handler` and `context` primitives, allowing handlers to be composed flexibly. It includes provider-specific packages that wrap lower-level OAuth handlers to fetch user profiles after authentication. The codebase is well-structured, thoroughly tested, and demonstrates strong software engineering practices with clean abstractions and attention to security details.