Awesome

Periodical

A calendar to track your menstruation and calculate possible fertile days

Translation:

Albert Kannemeyer, Sébastien Gravier, Primokorn, Valerio Bozzolan, Ingrid Spangler, Wjatscheslaw Stoljarski, Pander, Laura Arjona Reina, Naofumi Fukue, Tomasz Terka, Nikoletta Karasmani, Yaron Shahrabani, Inbar Gover, Turan Guliyeva, Enara Larraitz, Rza Sharifi, Mevlüt Erdem Güven

If you want to help with the translation, you can join the project on Crowdin:

https://crwd.in/periodical

This program is free software: you can redistribute it and/or modify it under the terms of the GNU 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.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

"Periodical" is a menstruation calendar with calculation of the fertile days according to Knaus-Ogino originally developed by Arno Welzel.

WARNING: It is not recommended to use this calendar to avoid pregnancy! There are more accurate methods, like measuring the basal body temperature.

Source:
https://github.com/arnowelzel/periodical

Download latest version at Google Play:
https://play.google.com/store/apps/details?id=de.arnowelzel.android.periodical

Download latest version at F-Droid:
https://f-droid.org/repository/browse/?fdid=de.arnowelzel.android.periodical

Download latest version as APK:
http://arnowelzel.de/download/Periodical.apk

Tools to used to build this project:

Android Studio
http://developer.android.com/tools/studio/index.html