This text presents contributions to efficient high-order finite element solvers in the context of the project ExaDG, part of the DFG priority program 1648 Software for Exascale Computing (SPPEXA). The main algorithmic components are the matrix-free evaluation of finite element and discontinuous Galerkin operators with sum factorization to reach a high node-level performance and parallel scalability, a massively parallel multigrid framework, and efficient multigrid smoothers. The algorithms have been applied in a computational fluid dynamics context. The software contributions of the project have led to a speedup by a factor 3 − 4 depending on the hardware. Our implementations are available via the deal.II finite element library.