One more common tool that is fun to write and that I use pretty offen. A tool that converts timestamp to date.
Unix time (also known as POSIX time or Epoch time) is a system for describing instants in time, defined as the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970, not counting leap seconds.
Please note this date is only for Universal Coordinated Time (UTC) or also called Greenwich Mean Time (GMT).