Spying always used to be an essential part of the strategy of the companies, as it was always much more dangerous and it caused more loss in human life to risk a frontal assault against a walled city or castle than to use deception. Companies employed spies for several reasons: so as to be able to conquer a city, capture a wealthy person, or seize a shipment or treasure. On the other hand, the use of spies and military intelligence proved to be just as an important tool for the medieval cities or the regional authorities as well when they were preparing for the onslaught of the routiers, who arrived either in the form of companies or disguised as crusaders. In this paper, I will illustrate both sides of the coin: spying for and against the companies.