Convertdate allows you to generate calendars according to different historical or modern systems:

Available calendars:

* Bahai * Coptic (Alexandrian) * French Republican * Gregorian * Hebrew * Indian Civil * Islamic * Julian * Mayan * Persian * Positivist * Mayan * ISO * Ordinal (day of year) * Dublin day count * Julian day count

The holidays module also provides some useful holiday-calculation, with a focus on North American and Jewish holidays.

This package ships the Python 3 version.