Most research on gender and digital communication centers on how women use digital media, how they participate online, or how they are treated in online forums and social media. This article, in contrast, approaches gender from a behind the screen perspective. How algorithms and platforms are created, designed, and maintained, the affordances they provide for users and how they govern the ways users communicate with each other, has a major impact on digital communication. However, it is mostly men who create these technologies. Our study approaches technologies as socio-cultural, departing from the concept of network media logic. Empirically, it is based on (1) the review of a diverse body of literature from the history of programming, professional sociology, and computer science and documents such as the diversity reports from tech giants, as well as on (2) 64 semi-structured expert interviews conducted with male and female programmers in seven countries over a time-period of four years. Results show that the gender gap continues to run deep. We report results in four dimensions: professional culture, pervasive stereotypes, lack of role models and typical career paths.