Restricted Data is a nuclear history blog created and run by Alex Wellerstein, a historian of science. It explores nuclear secrecy, past and present, through historical research, commentary, news, and notes. The site also documents Wellerstein’s work developing NUKEMAP, an interactive tool for examining the potential effects of nuclear detonations. Planned improvements include updated population data, expanded casualty estimates, analysis of impacts on schools, hospitals, religious institutions, and cultural sites, and more detailed fallout modeling.

Alongside NUKEMAP, Wellerstein is developing the Atomic Weapons Effects Library, an open-source JavaScript framework intended to bring different nuclear-effects models together and make them easier to use and evaluate. The blog shares details about the research, data, software, and technical decisions behind these projects, including efforts to improve accessibility and reduce operating costs. Restricted Data offers readers an informed perspective on nuclear history and the methods used to study nuclear weapons and their consequences. Its articles combine historical context with discussion of contemporary tools and research, making the site a resource for people interested in nuclear issues, science, and public understanding.