Turnitin is a cloud-based solution with capabilities in originality (Similarity) checking and online grading using its Originality Check and Grade Mark tools.

Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share your research sources. Zotero is the only research tool that automatically senses content in your web browser, allowing you to add it to your personal library with a single click.

Mendeley is a desktop and web-based citation tool, but more than that, it is a community of researchers. You can search through the millions of papers it contains from other Mendeley users, share your references and papers with collaborators, join public discussion groups, and discover other researchers in your field.