ADIF or Adif may refer to:

• Amateur Data Interchange Format, a file format to exchange amateur radio contact data
• Audio Data Interchange Format, a file format to exchange Advanced Audio Coding (AAC) data
• Adif (Administrador de Infraestructuras Ferroviarias), the state company responsible for railway infrastructure (track and stations) in Spain
• Administración de Infraestructuras Ferroviarias Sociedad del Estado (ADIF), the state company responsible for railway infrastructure in Argentina

ADIF (, an acronym of Administrador de Infraestructuras Ferroviarias) is a Spanish state-owned company under the responsibility of the Ministry of Public Works and Transport, charged with the management of most of Spain's railway infrastructure, that is the track, signaling and stations. It was formed in 2005 in response to European Union requirements to separate the natural monopoly of infrastructure management from the competitive operations of running train services. It is the legal successor of RENFE, FEVE (Ferrocarriles de Vía Estrecha), and GIF (Gestor de Infraestructuras Ferroviarias).