Paste a Unix timestamp, an ISO 8601 date, a Windows file time or a spreadsheet serial number and see every other spelling of the same moment at once. It works out which unit you gave it — ten digits is seconds, thirteen is milliseconds — and lets you correct the guess in one tap.
There is a live clock too, with the current epoch time in seconds and milliseconds, ready to copy. Everything is computed from your own device's clock; nothing is fetched and nothing is sent.