anywhen is a tiny date formatter built entirely on the native Intl browser API. One function, one options object, three modes.

The browser already knows how to format dates in 200+ languages. anywhen just makes that API pleasant to use.

import { anywhen } from 'anywhen'

anywhen(date)
// "yesterday, 2:35 PM"  — smart mode (default)

anywhen(date, { mode: 'absolute', locale: 'en' })
// "Feb 5, 2016"

anywhen(date, { mode: 'relative', locale: 'en' })
// "3 hours ago"

npm install anywhen
# or
pnpm add anywhen
# or
yarn add anywhen

The single entry point. Pass a date, optionally pass options.

anywhen(input)
anywhen(input, options?)

anywhen(date)
// runtime locale, smart mode

anywhen(date, { locale: 'en' })
// "yesterday, 2:35 PM"

anywhen(date, { mode: 'relative', locale: 'en', numeric: true })
// "1 day ago"

anywhen(date, {
  mode: 'absolute',
  locale: 'en',
  format: { weekday: 'long', month: 'long', day: 'numeric', year: 'numeric' },
})
// "Friday, February 5, 2016"

The mode option picks the rendering strategy. Each mode reads only the options that apply to it — the rest are ignored.

anywhen(date, { mode: 'absolute', locale: 'en' })
// "Feb 5, 2016"

anywhen(date, {
  mode: 'absolute',
  locale: 'en',
  format: { hour: '2-digit', minute: '2-digit' },
})
// "2:35 PM"

anywhen(date, {
  mode: 'absolute',
  locale: 'en',
  format: { month: 'long', year: 'numeric' },
  timeZone: 'Europe/Belgrade',
})
// "February 2016"

anywhen(date, { mode: 'relative', locale: 'en' })
// "3 hours ago"
// "yesterday"
// "in 2 weeks"

anywhen(date, { mode: 'relative', locale: 'en', numeric: true })
// "1 day ago"   — disables auto-phrases
// "1 week ago"

By default, smart and relative modes use the current time. In React SSR or Next.js, pass a stable now value to avoid hydration drift.

import { anywhen } from 'anywhen'

export function PostMeta({ createdAt, requestTime }: {
  createdAt: string
  requestTime: string
}) {
  return (
    <time dateTime={createdAt}>
      {anywhen(createdAt, {
        locale: 'en',
        now: requestTime,
        timeZone: 'Europe/Belgrade',
      })}
    </time>
  )
}

timeZone controls both the displayed clock and the smart calendar boundaries for today, yesterday, and weekday output.

All inputs accept three formats interchangeably.

// Date object
anywhen(new Date())

// Unix timestamp (milliseconds)
anywhen(Date.now())
anywhen(1704499200000)

// ISO string
anywhen('2016-02-05T14:00:00Z')
anywhen('2016-02-05')

Same calls in a few languages — no extra setup, no locale files.

// smart mode
anywhen(date, { locale: 'de' })   // "gestern, 14:35"
anywhen(date, { locale: 'ru' })   // "вчера, 14:35"
anywhen(date, { locale: 'fr' })   // "hier, 14:35"

// absolute mode
anywhen(date, { mode: 'absolute', locale: 'ja' })   // "2016年2月5日"
anywhen(date, { mode: 'absolute', locale: 'ar' })   // "٥ فبراير ٢٠١٦"
anywhen(date, { mode: 'absolute', locale: 'ru' })   // "5 февр. 2016 г."

// relative mode
anywhen(date, { mode: 'relative', locale: 'de' })   // "vor 3 Stunden"
anywhen(date, { mode: 'relative', locale: 'fr' })   // "il y a 3 heures"
anywhen(date, { mode: 'relative', locale: 'tr' })   // "3 saat önce"

Pass any valid BCP 47 language tag — including regional variants like en-GB, zh-TW, or pt-BR. Locale is optional; when omitted, native Intl uses the runtime locale. Fallback arrays like ['sr-Latn-RS', 'en'] also work.

anywhen uses Intl.RelativeTimeFormat and Intl.DateTimeFormat — both widely supported.

A few things worth knowing before you ship: