PlanetsCentral

AutoTroll had a trn checker. Besides NAVGAP, I mostly played on AutoTroll sites so I know I'd always get a message saying my turn was good.

As far as I know, AutoTroll uses chktrn.exe, which basically only checks that your turn file actually is a turn file that belongs to the current turn. So it will tell you when your turn is stale, but not when you got a red error due to mismatching shiplist files on your side.

Actually, PlanetsCentral checks for stale turns internally without need of an external checker.

It will send you a message with your status, of course. If you upload the turn through the website, you will get the status immediately.

--Stefan