The open-source software movement has been an unprecedented driver of global innovation and productivity growth. By sharing code that runs databases, smartphones and designs semiconductors for free – and letting anyone contribute to upgrading it and patching its bugs – OSS, as it is known, has spared companies from the need to reinvent countless wheels, accelerating the growth of the $475 billion global software industry. Yet rising geopolitical tensions are putting the movement’s future economic contribution at risk.