The National Science Foundation Network (NSFNet) is a wide area network that was developed by the National Science Foundation to replace ARPANET as the main network linking government and research facilities.

NSFNet was a major force in the development of computing infrastructure and enhanced network services. By making high-speed networking available to national computer centers and inter-linked regional networks, NSFNet created a network of networks, which laid the foundation for today's Internet.

NSFNet was dismantled in 1995 and replaced with a commercial Internet backbone.