Nice idea!
Added the command and updated the docs at https://csgo-stats.net/tools/nightbot
Thank you for the feedback 
Looking for a better example of how to use the !rank command.
$(urlfetch https://csgo-stats.net/api/nightbot/rank/$(demnd)/YOURCUSTOMURL)
the bold part is where I am confused, is that my steam url like http://steamcommunity.com/profiles/76561198149238583/ ,or is it the csgo-stats.net url for my profile?
Sorry for the super late question, but I can’t find any other examples elsewhere unfortunately.
How do I remove the link in the response? there is a maximum of 400 characters, and I want to add several fetchurl in the same command
You can use Nightbot’s eval variable to remove the link.
Stats for a specific user
!stats
$(eval `$(urlfetch https://csgo-stats.net/api/nightbot/stats/$(channel)/YOURCUSTOMURL)`.replace(/ - .*/, ""))
Your watchers stats
!mystats [CUSTOMURL]
$(eval `$(urlfetch https://csgo-stats.net/api/nightbot/stats/$(channel)/$(1))`.replace(/ - .*/, ""))
Show your current inventory
!inventory
$(eval `$(urlfetch https://csgo-stats.net/api/nightbot/inventory/$(channel)/YOURCUSTOMURL)`.replace(/ - .*/, ""))
Your always up-to-date rank
!rank
$(eval `$(urlfetch https://csgo-stats.net/api/nightbot/rank/$(channel)/YOURCUSTOMURL)`.replace(/ - .*/, ""))
VAC status
!vac [steamname]
$(eval `$(urlfetch https://vac-check.com/api/$(channel)/$(1))`.replace(/ - .*/, ""))
Cool! Now I don’t have to worry about the link being posted several times in the same response Thanks! 
Thank you for the feedback.