downtimed is a program that monitors operating system downtime, uptime, shutdowns, and crashes and records such events. At OS startup it logs information about previous downtime. It then periodically updates a time stamp file on the disk, which is used to determine the approximate time when the system was last up and running. During a graceful system shutdown, it records a time stamp in another file. The downtimes(1) command line tool can be used to inspect records of past downtime.
I want to keep downtimed as simple as possible: it should do only a single thing and do it well. And that is keeping track of the downtimes. uptimed has a lot of bloat which does not belong to downtimed. uptimed seems targeted for Linux where as downtimed is supposed to run on any (UNIXish) popular server platform. Anyone is free to merge the functionality in to updowntimed (or whatever) as both are free software.