PDFView is based on the excellent MuPDF library. It is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. The APK is provided here for convenience, you can download the source code at https://www.acadoid.com/src/pdfview.tgz.
NOTE: PDFView is not a PDF viewer in the sense of displaying PDF files, there is no graphical user interface and the app is not supposed to be started directly. Instead, it is a PDF viewer that provides PDF rendering service to other apps via a documented interface. At the moment, the app is only used by LectureNotes, but all other Android developers are invited to include an interface to PDFView into their apps and use PDFView for PDF rendering. Details of the interface can be found in the source of PDFView.
We would love to hear from you, please send feedback and feature requests to us by email. If you encounter a problem with the app, please email us and we will do our very best to fix it quickly.
* requires only minimal permissions and no internet connection (we do respect your privacy!)
* allows other apps to convert a PDF file into a set of PNG files with a given resolution, either a single page or a page set