Calendor is a simple material calendar designed with functionality and ease of use in mind. 

All national and religious holidays are marked accurately for the current year, and will be updated for the following years. 

Calendor is an open-source project, you can check the source code here:

https://github.com/Tenkei/Calendor 

Features: 

• Events and holidays accurately marked  
  
• Add events to device calendar 
  
• Sticky notification on your preference 
  

To update:

Please first uninstall the previous version, Keep in mind that by uninstalling the app the created events do persist and shall not be deleted.