Question 1

Seconds or milliseconds?

Accepted Answer

A Unix timestamp is in seconds, while JavaScript's Date.now returns milliseconds. Mixing them throws dates back to 1970 or far into the future — 10 digits means seconds, 13 means milliseconds.

Question 2

How are timezones handled?

Accepted Answer

A timestamp is always UTC; the timezone only matters at display time. The tool shows local time and UTC side by side so the offset doesn't slip past you.

Timestamp Converter