The technical requirements of the free exchange of scientific literature, which the “Budapest Declaration” promulgated in 2002, had already been suggested by a research group in 1999. An HTML transfer protocol (OAI-PMH) was to standardise the dissemination of bibliographic metadata. This rule set proved to be a lasting success and became the core of open-access technology. It will be outlined and its history traced. As it progressed, weaknesses and the extensibility of the protocol became apparent. The development of powerful search engines and powerful big-data algorithms put it in a new socio-political environment, still uncertain in its implications.