https://unixtimestamp.live/guides Guides to Unix time, time zones and date formats. en https://unixtimestamp.live/guides/monotonic-clocks https://unixtimestamp.live/guides/monotonic-clocks Subtracting two Unix timestamps to measure a duration gives the wrong answer whenever the clock is adjusted — including negative durations. Mon, 09 Feb 2026 00:00:00 GMT https://unixtimestamp.live/guides/epoch-milestones https://unixtimestamp.live/guides/epoch-milestones 1234567890, 2147483647, 1000000000 — the timestamps worth recognising, and the boundaries worth having in your test fixtures. Sat, 07 Feb 2026 00:00:00 GMT https://unixtimestamp.live/guides/cron-jobs-and-time-zones https://unixtimestamp.live/guides/cron-jobs-and-time-zones A job at 02:30 local never runs in spring and runs twice in autumn. The fix is to schedule in UTC and make the job idempotent. Thu, 05 Feb 2026 00:00:00 GMT https://unixtimestamp.live/guides/jwt-expiry-and-clock-skew https://unixtimestamp.live/guides/jwt-expiry-and-clock-skew Pass Date.now() into exp and you have issued a token expiring in the year 56,000. Here is the whole class of timestamp bug around JWTs. Tue, 03 Feb 2026 00:00:00 GMT https://unixtimestamp.live/guides/negative-unix-timestamps https://unixtimestamp.live/guides/negative-unix-timestamps -86400 is 31 December 1969. Most languages handle it correctly; a surprising number of databases, APIs and validators do not. Sun, 01 Feb 2026 00:00:00 GMT https://unixtimestamp.live/guides/rfc-3339-vs-iso-8601 https://unixtimestamp.live/guides/rfc-3339-vs-iso-8601 Almost the same, but not quite a subset in either direction. If you are writing an API, target the overlap. Wed, 28 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/storing-timestamps-in-databases https://unixtimestamp.live/guides/storing-timestamps-in-databases The column type you pick determines whether your dates survive a server move, a time zone change and the year 2038. Most defaults are wrong. Sun, 25 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/time-zones-vs-utc-offsets https://unixtimestamp.live/guides/time-zones-vs-utc-offsets An offset like +05:30 tells you what a clock read. Asia/Kolkata tells you which clock, and what it will read next year. That difference matters for future dates. Thu, 22 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/daylight-saving-bugs https://unixtimestamp.live/guides/daylight-saving-bugs The missing hour and the repeated hour cause skipped jobs, double charges and impossible timestamps. All of it is preventable by scheduling in UTC. Tue, 20 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/utc-vs-gmt https://unixtimestamp.live/guides/utc-vs-gmt They agree to within a second, which is why the difference is usually ignored — and exactly why it surprises people when it finally matters. Sun, 18 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/leap-seconds https://unixtimestamp.live/guides/leap-seconds Twenty-seven seconds have been inserted into UTC since 1972, and Unix time represents none of them. Usually harmless, occasionally catastrophic. Thu, 15 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/iso-8601-explained https://unixtimestamp.live/guides/iso-8601-explained The interchange format that removes ambiguity from dates — and the handful of its features you should never use. Mon, 12 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/seconds-vs-milliseconds https://unixtimestamp.live/guides/seconds-vs-milliseconds Ten digits or thirteen. Get it backwards and your date lands either in January 1970 or somewhere around the year 55,000. Here is how to make the bug impossible. Sat, 10 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/year-2038-problem https://unixtimestamp.live/guides/year-2038-problem At 03:14:07 UTC on 19 January 2038, a signed 32-bit time_t runs out of room and wraps to 1901. Most systems are fine. The ones that are not are hard to find. Thu, 08 Jan 2026 00:00:00 GMT https://unixtimestamp.live/guides/what-is-unix-time https://unixtimestamp.live/guides/what-is-unix-time A single integer that identifies any instant, anywhere on Earth, with no time zone attached. Here is where it came from and what it deliberately leaves out. Mon, 05 Jan 2026 00:00:00 GMT