# HowardHinnant/date

A date and time library based on the C++11/14/17 <chrono> header

Repository: https://github.com/HowardHinnant/date
Canonical: https://ross.abutalabs.com/products/date
Language: C++
License: NOASSERTION
License Family: other
Topics: date, datetime, timezone, calendar, time, iana-database, timezone-library
Last push: 2026-08-20T18:37:40+00:00

## Health v2 (maintenance only)
Score: 86/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 98, release rhythm 63, longevity 100
- inputs: {"age_days": 4065, "days_push": 13, "days_rel": 37, "gap_med": 219, "n_releases_24m": 4}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3430, forks 739 (observed 2026-08-28T04:08:04.023405+00:00)

## What it is
A C++11/14/17 date and time library built on <chrono>, providing field types like year_month_day, timezone support via a complete IANA tz database parser, and ISO week, Julian, and Islamic calendars. Its core parts were adopted into the C++20 standard.

## Use cases
- parse and format dates in C++
- convert between timezones in C++
- handle daylight saving time correctly
- work with ISO week dates
- compute with leap seconds

## When to choose
- you need robust date/time handling in C++ pre-C++20
- you need IANA timezone database access in C++
- you want a header-only date library

## When to avoid
- you are on C++20 or later and can use std::chrono directly
- you need date/time handling in a language other than C++

## Facets
- artifact type: library
- maturity: stable
- function: date-time
- domain: developer-tools, cross-platform
- platform: cpp, cross-platform
- tags: header-only, chrono, timezone, iana-tz-database, calendar, c++20-chrono-preview

## Member repositories
- HowardHinnant/date (main) score 86

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:04.023405+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 2026-08-29T18:37:47.015327+00:00, confidence not recorded.
  - readme: https://github.com/HowardHinnant/date (fetched 2026-08-28T04:08:04.023405+00:00, sha cb9de25e8d67)
- Data as of 2026-08-30T08:39:29.467469+00:00.