Apps to PDF annotation

BibSonomy is a powerful social bookmarking and publication-sharing platform, designed for researchers and knowledge workers. It allows users to collect, organize, and share literature, documents, and web resources using collaborative tagging and bibliography management features.

Documents by Readdle is a powerful file manager, media player, and document viewer for iPhone and iPad. It allows users to organize files, download content, view various document types, listen to music, watch videos, and annotate PDFs all within a single application.

colwiz is a comprehensive research management software designed for academics and researchers. It provides tools for organizing research papers, generating bibliographies, collaborating with peers, and managing research projects.

CloudScan is a user-friendly scanning software designed for efficiently digitizing documents, photos, and images into multipage PDF files. It offers core functionalities like scanning, PDF management (split, merge, edit), and built-in OCR capabilities, making it a comprehensive solution for basic document handling on a single computer.

Xodo is a comprehensive, cross-platform PDF solution offering a wide array of tools for viewing, annotating, editing, signing, and creating PDF documents. With robust collaboration features and seamless cloud integration, it caters to both individual and professional use.

PDFescape is a versatile online PDF editor and form filler.

ThinkFree Office is a comprehensive office suite written in Java, providing a robust and cross-platform solution for document creation, editing, and collaboration on Windows, Linux, macOS, and Android.

Benubird PDF was a document organizer designed to help users manage their PDF collections efficiently. It offered features like tagging, metadata management, and integration with office suites to streamline document workflow and search.

Stylus Labs Write is a unique word processor designed specifically for handwritten input on tablets and other stylus-enabled devices. It offers a fluid writing experience with tools tailored for digital ink, including robust erasing, flexible formatting, and organizational features.

ReadCube is a powerful desktop and web-based reference management and PDF annotation tool designed for researchers and students.

Master PDF Editor is a comprehensive PDF editing suite for Windows, macOS, and Linux. It empowers users to create, edit, view, annotate, and sign PDF documents with a robust set of tools.

PDF-XChange Editor is a powerful, free PDF editor and viewer for Windows. It offers a wide range of tools for creating, editing, annotating, and managing PDF documents, including OCR, form creation, and advanced security features. Despite its extensive capabilities, it remains lightweight and efficient.

Preview is the native image and PDF viewer for macOS. It offers essential tools for viewing, annotating, and basic editing of these file types directly within the Apple ecosystem. Designed for efficiency and low resource use, Preview provides a seamless and integrated experience for handling common document and image formats on Mac computers.

Diigo is a comprehensive online tool designed for researchers, students, and lifelong learners to collect, organize, annotate, and share information found on the web. It acts as a powerful bookmarking service combined with robust annotation capabilities for web pages, PDFs, and documents.

Mendeley is a freemium reference manager and academic social network designed for researchers. It helps organize, manage, and share research papers, generate citations, and collaborate on projects.

Qiqqa is a robust, award-winning research management software designed for academic and commercial researchers. It offers comprehensive tools for managing, annotating, and analyzing PDF documents, facilitating collaboration, bibliography generation, and knowledge discovery within research projects.

PDF-XChange Viewer is a versatile and lightweight PDF reader and editor. It offers a wide array of features for viewing, annotating, and manipulating PDF documents, including OCR capabilities and form filling, all within a user-friendly interface.

Adobe Acrobat Reader DC is the venerable and widely adopted standard for interacting with PDF documents. It provides robust tools for viewing, printing, signing, and commenting on PDF files across various devices and platforms.

Evernote is a popular cross-platform note-taking application designed to capture, organize, and manage your notes. It offers robust syncing capabilities across devices and includes features like web clipping, OCR for images, and integration with other services to streamline your productivity and information management.

Citavi is a comprehensive reference management and knowledge organization software designed for students, academics, and researchers. It facilitates the entire research process, from information gathering and organization to task management and bibliography generation, enhancing productivity and streamlining academic work.