Open-source technology is built on the principles of openness/sharing, public interest, and collaboration. However, amid intensifying China–US geopolitical competition, it has become a core element in their technological rivalry. Both nations are actively advancing open-source technology and promoting its application and development through state power. The United States utilizes open-source technology to maintain its technological leadership and shape the global digital ecosystem. It employs a combination of policies, investment, and export controls to protect its national security and economic interests while promoting open-source initiatives to foster innovation and collaboration. However, against the backdrop of strategic competition between the two countries, the U.S. concerns over Chinese access to open-source technologies have intensified. China, pursuing high-quality self-reliance within an open world economy, mobilizes national strategies, enterprise innovation and expanding communities to accelerate indigenous RISC-V chips, AI frameworks and operating systems, while actively shaping international standards that reflect the interests of developing countries. This dynamic is reconfiguring global governance such that licensing regimes, semiconductor supply chains, and large-model diffusion protocols are increasingly fragmented along geopolitical lines, increasing the risk of technological decoupling. To avert technological fragmentation and the erection of a “digital iron curtain,” states should institutionalize a technical mutual-trust mechanism.