By default : use lowercase, uppercase, numbers, and try not same letters.

Only one key : /api/{length}[/d]
Many keys : /api/{length}-{quantity}[/d]
Add punctuation : /api/{length}-p-{quantity}[/d]
Set all : /api/{length}-{lowercase}-{uppercase}-{numbers}-{punctuation}-{quantity} (0 or 1 for settings)
Add /d in end for see parameters setted (debug)
Or add /str in end for get text instead of json (only one key retourned)