Update: Old post is replaced by the one below.
1- EasyBib
‘EasyBib is an intuitive information literacy platform that provides citation, note taking, and research tools that are easy-to-use and educational. EasyBib is not only accurate, fast, and comprehensive, but helps educators teach and students learn how to become effective and organized researchers.’
3- Mendeley
‘Mendeley is a free reference manager and academic social network. Make your own fully-searchable library in seconds, cite as you write, and read and annotate your PDFs on any device.’
4- Zotero
‘Zotero is a powerful, easy-to-use research tool that helps you gather, organize, and analyze sources and then share the results of your research.’
5- Paperpile
‘Manage your research library right in your browser: Save time with a smart, intuitive interface, access your PDFs from anywhere, format citations within Google Docs… and much more!’