This plugin displays a time on to each player's hotbar and the time can be stopped or paused.

UPDATE: Placeholder support! %stopwatch_time% for time message and %stopwatch_seconds% for raw seconds passed.

NOTE: this plugin should work for every version of minecraft even new ones without updating it as the spigot hotbar api has been stable since 1.9

/st start - Starts the timer or resets it if already running
/st stop - Stops the timer
/st showall - to show timer message to all players (by default)
/st show [playername] - to show message to specific player
/st pause - Pauses the timer and unpauses if already paused
/st help - Shows all commands and usages
/st item - Gives 3 items which will stop, start or pause the timer when clicked.
/st offset [seconds] offset the timer by the given amount of seconds, positive or negative
/st endsec [seconds] the timer will automatically stop at this time
/st message [message] change how the message will be displayed to the hotbar, must include {0} which is a placeholder for the time.
NEW
/st togglems toggles whether milliseconds show, on by default

stopwatch.admin is the permission needed to use the commands.
stopwatch.default is the permission needed to see the timer message
Example /st message &6Time: &a{0}

You can also set the message in the config but you have to restart for it to take effect