Open Trivia DB: Free to use, user-contributed trivia question database.

• https://opentdb.com
• https://opentdb.com/browse.php
• https://opentdb.com/trivia_add_question.php
• https://opentdb.com/api_config.php
• http://forums.pixeltailgames.com/
• https://opentdb.com/login.php
• https://creativecommons.org/licenses/by-sa/4.0/
• http://www.towerunite.com
• http://www.pixeltailgames.com