WhatsApp began supporting third-party messaging services in late 2025 in compliance with the EU's Digital Markets Act (DMA), which requires major tech companies to enable interoperability with alternative chat platforms. Threema has chosen not to implement interoperability with WhatsApp, citing concerns over user privacy and security, as differences in user identification methods could lead to compromises that weaken privacy protections. Threema believes that interoperability could reinforce WhatsApp's market dominance, reducing the incentive for users to adopt the Threema app. Additionally, Threema's business model relies on app sales for revenue, and a drop in downloads due to interoperability could threaten this model. Consequently, Threema has decided against pursuing interoperability with WhatsApp to maintain its commitment to privacy and security.