lifex: a flexible, high performance library for the numerical solution of complex finite element problems

Numerical simulations are ubiquitous in mathematical and computational modeling, where many industrial and clinical applications are required to deal with multiphysics problems and with complex systems characterized by multiple spatial and temporal scales. This document introduces the design and the capabilities of lifex, an open source C++ library for high performance finite element simulations of multiphysics, multiscale and multidomain problems. lifex offers a versatile solution to answer the emerging need for efficient computational tools that are also easily approachable by a wide community of users and developers. We showcase illustrative examples of use, benchmarks, advanced application scenarios and demonstrate its parallel performance up to thousands of cores.