spencermountain/spacetime

Health v2 · maintenance only

Flags: no_license

Adoption not part of the score

4108 stars · 190 forks observed · 2026-09-29

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

Spacetime is a lightweight, zero-dependency JavaScript library for calculating dates and times across timezones. It provides a Moment-like immutable API that handles daylight savings, leap years, and hemisphere-aware date math.

Use cases

• convert a date to a remote timezone like Europe/Paris
• calculate how many days until the end of the year
• figure out what time it was 11 hours ago
• check if it's lunchtime in France right now
• add or subtract months while keeping the time-of-day stable across DST shifts
• format dates and times in different timezones without the Intl API

When to choose

• you need timezone-aware date math in a small bundle (~40kb, zero dependencies)
• you want a Moment-like immutable API without Moment's weight
• you need DST, leap-year, and hemisphere handling for most common cases

When to avoid

• you need exhaustive, standards-perfect timezone handling for edge cases
• you need locale-aware formatting or parsing of arbitrary date strings
• you're already using a full-featured date library like date-fns or Luxon

Facets

library · maturity stable

date-time sdk developer-tools web-development cross-platform browser timezone-conversion date-math daylight-savings immutable-api zero-dependencies moment-like nodejs javascript

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