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:
Pen&PDF is Copyright 2015-2018 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
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 .
Due to limitations concerning the supported character encoding in the underlying library, Pen&PDF does not cope well with certain pdf forms.