WDK by Tether is a fully open-source, self-custodial wallet development toolkit designed to build advanced mobile and desktop wallet experiences for Bitcoin and Tether tokens. The platform is modular, independent, and resilient, enabling developers to create secure financial custody solutions for both humans and autonomous AI agents. WDK provides the foundation for decentralized financial control in a world where machines and humans coexist, offering robust self-custodial capabilities even in uncertain scenarios.