Qiqqa is by far the strongest solution for research and managing pdf's. Zotero, named as a comparison is weak as it does not allow pdf;s to be loaded into its interface - you need to use a pdf reader, which defeats its whole purpose. With Qiqqa documents in a library can be searched together. It has excellent maps of your libraries. It is not prefect, having a few glitches, but still is the only one of its kind.
Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.
Dexoc - Read writing from Dexoc on Medium. Dexoc is leading custom software development company that provides Web & Mobile application development services across diversified industries.
Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
BargeOps - BargeOps is a full-featured towing, fleet, freight contract, and terminal management software solution that provides management and planning, billing, and reporting functionality for Inland Marine Companies
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .
SumatoSoft - Software Development Company: We help companies to digitalize their businesses. Properly set processes. Transparent cooperation. Predictable delivery.