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Convert Unix timestamps to human-readable dates and back, in any timezone. Supports both second and millisecond precision, and outputs ISO 8601 and RFC 3339 formats.
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A Unix timestamp is the number of seconds that have elapsed since January 1, 1970, 00:00:00 UTC (the Unix epoch). It is the standard way computers represent points in time, and it is the same in every timezone. Millisecond timestamps are the same value multiplied by 1,000.
Count the digits. Second timestamps are 10 digits long (valid until the year 2286), while millisecond timestamps are 13 digits. For example, 1720000000 is in seconds, while 1720000000000 is the same moment in milliseconds.
RFC 3339 is a stricter profile of the ISO 8601 standard, designed for internet use. Both look like 2024-07-03T09:46:40Z, but RFC 3339 requires a colon in the timezone offset and permits a smaller subset of formats. Most modern APIs accept either.