Unix timestamps are everywhere in a developer's day: API responses carry created_at fields as bare numbers, log lines are stamped in epoch milliseconds, JWT expiry claims count seconds, and database rows store integers where humans expect dates. This converter translates in both directions and shows the live current epoch in seconds and milliseconds, ticking in real time.
Paste any epoch value and the tool detects whether it is seconds or milliseconds, then shows that moment as local time, UTC, ISO 8601 and relative time. Going the other way, pick a date and time to get its epoch value ready to drop into a query or a test fixture. It is the quickest way to check whether a token expired before the errors started.
Converting a timestamp is pure arithmetic, and this page keeps it that way: every conversion is calculated by JavaScript running locally, using your device's own clock and timezone. The values you enter, which can reveal exactly when events happened in your systems, are never sent anywhere or stored by anyone.
It is the instant 00:00:00 UTC on 1 January 1970, the zero point from which Unix time counts. A timestamp is simply the number of seconds, or milliseconds, elapsed since that moment. Being a single number tied to UTC, it is unambiguous across timezones.
By length, for any modern date: a timestamp in seconds is currently 10 digits, while milliseconds give 13. So 1700000000 is seconds and 1700000000000 is milliseconds. This tool uses the same digit-count check to detect the unit automatically.
Only if you maintain systems that store Unix time in a signed 32-bit integer, which overflows on 19 January 2038. Modern platforms use 64-bit values, so the concern is mainly legacy embedded devices and very old schemas.