The EPW (Electron-Phonon coupling using Wannier functions) software is a Fortran90 code that employs density-functional perturbation theory and maximally localized Wannier functions to accurately and efficiently compute electron-phonon couplings and related properties in solids. The EPW v4 program can calculate electron and phonon self-energies, linewidths, electron-phonon scattering rates, coupling strengths, transport spectral functions, electronic velocities, resistivity, anisotropic superconducting gaps, and spectral functions within the Migdal-Eliashberg theory. The code supports spin-orbit coupling, time-reversal symmetry in non-centrosymmetric crystals, polar materials, and k and q-point parallelization. Significant efforts have been made to optimize and parallelize the code, achieving a nearly tenfold speedup compared to previous versions. A computer test farm ensures the stability and portability of the code on various compilers and architectures. Since April 2016, EPW v4 has been fully integrated into and distributed with the Quantum ESPRESSO package. The manuscript provides an overview of the new features and improvements, including the integration into Quantum ESPRESSO, the implementation of the superconducting formalism, and the parallelization and speedup of the software. Examples of physically relevant applications are also discussed, such as spectral functions and linewidths of B-doped diamond, scattering rates of undoped Si, resistivity of Pb with and without spin-orbit coupling, electron-phonon matrix elements for GaN, and superconducting properties of MgB2.The EPW (Electron-Phonon coupling using Wannier functions) software is a Fortran90 code that employs density-functional perturbation theory and maximally localized Wannier functions to accurately and efficiently compute electron-phonon couplings and related properties in solids. The EPW v4 program can calculate electron and phonon self-energies, linewidths, electron-phonon scattering rates, coupling strengths, transport spectral functions, electronic velocities, resistivity, anisotropic superconducting gaps, and spectral functions within the Migdal-Eliashberg theory. The code supports spin-orbit coupling, time-reversal symmetry in non-centrosymmetric crystals, polar materials, and k and q-point parallelization. Significant efforts have been made to optimize and parallelize the code, achieving a nearly tenfold speedup compared to previous versions. A computer test farm ensures the stability and portability of the code on various compilers and architectures. Since April 2016, EPW v4 has been fully integrated into and distributed with the Quantum ESPRESSO package. The manuscript provides an overview of the new features and improvements, including the integration into Quantum ESPRESSO, the implementation of the superconducting formalism, and the parallelization and speedup of the software. Examples of physically relevant applications are also discussed, such as spectral functions and linewidths of B-doped diamond, scattering rates of undoped Si, resistivity of Pb with and without spin-orbit coupling, electron-phonon matrix elements for GaN, and superconducting properties of MgB2.