Just tried to go to the Grok Debugger (https://grokdebug.herokuapp.com/) and it's giving me an application error...
Give http://grokconstructor.appspot.com a try, then 
UPDATE: Kibana 6 now includes a "Grok Debugger" tab if you have X-Pack installed:
1 Like
Yeah, I found grokconstructor after I posted the message. Very nice!
Aaand Grok Debugger is working again...
It's a community managed site, so it's not something we can directly help with unfortunately.