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.
The use of QDA software in social science research is so common that many people tend to see QDA software as a tool primarily for social science research. However, applications like MAXQDA are invaluable productivity tools for research analysts in industry or government as well.
Remarkably scalable, MAXQDA employs a database architecture that can handle research projects ranging in size from several dozen pages to tens of thousands of pages. Many projects today involve identifying connections found among information stored in PDF, Powerpoint presentations, Word documents, photos, videos, and audio recordings. MAXQDA allows users to code relevant sections of each document, identify interrelationships among documents, build relationships among diverse sets of documents and identify thematic trends.
MAXQDA features a simple 4 pane interface that makes it easy to use. The Document System- is where you place documents (text, images, video, or sound files) you want to analyse. The Document Browser is where you view the content of the document. The Coding System shows the various codes that you create and assign to documents. The Retrieved Segments Pane shows search results.
Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.
NVivo - Buy NVivo now for flexible solutions to meet your specific research and data analysis needs.
Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
ATLAS.ti - ATLAS.ti is a powerful workbench for the qualitative analysis of large bodies of textual, graphical, audio and video data. It offers a variety of sophisticated tools for accomplishing the tasks associated with any systematic approach to "soft" data.
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .
QualCoder - A very complete Free and Open Source Software (FOSS) Computer-Assisted Qualitative Data Analysis Software (CAQDAS) written in Python. It works with text, images, and multimedia such as audios and videos.