Cotonou, is generally safe during the day with locals being friendly and helpful. However, it may get a little unsafe after dark with instances of petty crime and occasional pickpocketing. It is highly advisable always to arrange your transportation and avoid walking alone at night. Always be aware of your surroundings, and take usual precautions as you would in any other city. Overall, while exploring Cotonou, it's better to be safe than sorry.