The Swedish dictionary is provided by The Swedish Academy (Svenska Akademien).
The Dutch dictionary is proprietary, created by TaalTik, using the OpenTaal dictionary as base material.
Wordfeud uses Retskrivningsordbogen 2001, made by Dansk Sprognævn.
Wordfeud uses "NSF-ordlisten", made by the Norwegian Scrabble Association (Norsk Scrabbleforbund).