paperly is described as 'Paperly is a paper reader, which aims to improve the whole experience of reading, note-taking and mind mapping. Three key features are provided: (1) WYSIWYG Citation; (2) Contextual Notebook; (3) Scholar Mind Graph' and is an app in the Office & Productivity category. There are four alternatives to paperly for a variety of platforms, including Mac, Windows, Linux, Online / Web-based and Safari. The best alternative is Zotero, which is both free and Open Source. Other great apps like paperly are Qiqqa (Free, Open Source), Mendeley (Freemium) and Highlights (Freemium).
Zotero is a free, easy-to-use Firefox/Chrome extension or standalone program to help you collect, organize, manage, search and cite your research sources directly in your favourite word processor, with 300 MB free online storage.
Mendeley helps manage and share academic knowledge: Mendeley Desktop is free academic software (Windows, Mac, Linux) for organizing and sharing research papers and generating bibliographies with 1GB of free online storage to automatically back up and synchronize your library...
Highlights is a PDF reader for note takers. Highlights lets you highlight text and select images in the PDF, but take notes in a regular text-editor. No more typing notes and comments into tiny text boxes.