Date and Time in Python

Since Python 3.9, the standard library's zoneinfo module provides IANA time zones, which removes the main reason to use pytz in new code. python-dateutil adds flexible parsing of date strings, relativedelta for calendar arithmetic such as adding a month, and recurrence rules. dateparser parses human-written dates, including relative expressions like "2 days ago", in many languages, which helps when scraping or reading user input.

Pendulum provides a datetime subclass that is time zone aware by default, with readable differences and durations. whenever takes a stricter approach: separate types for exact instants, zoned times and local times, so mistakes around daylight saving time become type errors rather than silent bugs; it has a Rust core with a pure Python fallback. Whatever library you use, store timestamps in UTC with time zone information and convert to local time only for display.