Amplify is free full featured accelerated mobile pages (AMP) template. It is a simple HTML template for Jekyll and static website or blog.
Ladda a beautiful user interface approach of integrating progress indicators in HTML buttons. It give a nice user experience as it immediately gives feedback to user that his/her requested operation is underway.
SB Admin 2 is a free responsive premium Bootstrap based Admin Panel Template. It features a dashboard template, a web-app UI starter. SB Admin 2 is an enhancement over its old SB Admin Template theme.
File upload is trivial to any web application. Prior to Java Servlet specification 3.0 upload to server required Apache Commons. Now its just a matter of writing a just any other file.