This document discusses strategies for incumbent firms to respond to threats from competitors offering free products. It begins by outlining factors to assess the seriousness of the threat, such as user growth rates and customer defection rates. Four response strategies are proposed based on these factors, ranging from immediately launching a free product to monitoring the situation. Additional strategies discussed include offering a better free product, upselling premium versions, cross-selling other products, charging third parties for access to users, bundling free products, and rethinking profit centers. Examples of companies that succeeded or failed against free competitors are provided. The document emphasizes adopting the mindset of low-cost rivals and anticipating their moves to effectively compete against free.