Hi all, I'm the developer. I built Mahbanou, a free Solar Hijri calendar with Iranian holidays and Zoroastrian observances, in Persian and English. It works offline, with no ads or payments.

iPhone/iPad (free): https://apps.apple.com/us/app/mahbanou-persian-calendar/id6815880718

The Android version is in a 14-day closed beta Google requires before release. If you'd like to help test, DM me your Gmail address so I can add you, then opt in here: https://play.google.com/apps/testing/dev.zubin.mahbanou

Feedback welcome, especially from anyone who follows the Shahenshahi or Kadmi calendars.