Particle accelerators are a key asset of the European Research Area. Their use spans from the large installations devoted to fundamental science to a wealth of facilities providing X-ray or neutron beams to a wide range of scientific disciplines. Beyond scientific laboratories, their use in medicine and industry is rapidly growing. Notwithstanding their high level of maturity, particle accelerators are now facing critical challenges related to the size and performance of the facilities envisaged for the next step of particle physics research, to the increasing demands to accelerators for applied science, and to the specific needs of societal applications. In this crucial moment for accelerator evolution, I.FAST aims at enhancing innovation in and from accelerator-based Research Infrastructures (RI) by developing innovative breakthrough technologies common to multiple accelerator platforms, and by defining strategic roadmaps for future developments. I.FAST will focus the technological R&D on long-term sustainability of accelerator-based research, with the goal of developing more performant and affordable technologies, and of reducing power consumption and impact of accelerator facilities, thus paving the way to a sustainable next-generation of accelerators. By involving industry as a co-innovation partner via the 17 industrial companies in the Consortium, 12 of which SME’s, I.FASTwill generate and maintain an innovation ecosystem around the accelerator-based RIs that will sustain the long-term evolution of accelerator technologies in Europe. To achieve its goals, I.FAST will explore new alternative accelerator concepts and promote advanced prototyping of key technologies. These include, among others, techniques to increase brightness and reduce dimensions of synchrotron light sources, advanced superconducting technologies to produce higher fields with lower consumption, and strategies and technologies to improve energy efficiency.