Pen&PDF is a PDF viewer and annotation app for Android built on top of MuPDF. Pen&PDF is open source. You can get the source code from GitHub: https://github.com/cgogolin/penandpdf LICENSE Pen&PDF is Copyright 2015-2016 Christian Gogolin This program 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. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. For more information on the GNU Affero General Public License see .</br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br>