# ariebovenberg/whenever

⏰ Type-safe datetimes for Python that get DST right. Rust or pure Python, your choice

Repository: https://github.com/ariebovenberg/whenever
Canonical: https://ross.abutalabs.com/products/ariebovenberg-whenever
Homepage: https://whenever.rtfd.io
Language: Python
License: MIT
License Family: permissive
Topics: datetime, mypy, python, timezones, type-safe, utc, rfc3339, utc-offsets, rust, cpython, pure-python, pypy
Last push: 2026-08-24T04:06:47+00:00

## Health v2 (maintenance only)
Score: 93/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 97, longevity 73
- inputs: {"age_days": 1027, "days_push": 9, "days_rel": 22, "gap_med": 10.0, "n_releases_24m": 37}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2398, forks 37 (observed 2026-08-28T04:06:43.735594+00:00)

## What it is
Whenever is a Python library providing type-safe datetime and timezone handling that prevents naive/aware mixing at the type level and correctly handles DST in all arithmetic. It offers both a fast Rust extension and a pure Python implementation.

## Use cases
- parse and format RFC 3339 timestamps safely
- avoid mixing naive and aware datetimes in Python
- handle daylight saving time correctly in datetime arithmetic
- convert datetimes between timezones and UTC offsets
- get faster datetime operations than the standard library
- add strict type checking for datetime usage with mypy

## When to choose
- you need DST-correct datetime arithmetic in Python
- you want type errors instead of runtime bugs for naive/aware mixing
- performance matters and you want faster-than-stdlib datetimes
- you want a choice between Rust-backed and pure Python implementations

## When to avoid
- you need a drop-in replacement for datetime.datetime
- your project cannot add third-party dependencies
- you need date parsing beyond datetime scope like natural language dates

## Facets
- artifact type: library
- maturity: active
- function: date-time, type-system, serialization
- domain: developer-tools, programming-languages
- platform: python, rust, cross-platform
- tags: datetime, timezone, dst, type-safety, mypy, rfc3339, utc, pure-python, algorithms

## Member repositories
- ariebovenberg/whenever (main) score 93

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:43.735594+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:34:18.359377+00:00, confidence not recorded.
  - readme: https://github.com/ariebovenberg/whenever (fetched 2026-08-28T04:06:43.735594+00:00, sha 7e245bba588e)
- Data as of 2026-08-30T08:39:29.467469+00:00.