turboTDDFT – a code for the simulation of molecular spectra using the Liouville-Lanczos approach to time-dependent density-functional perturbation theory. We introduce turboTDDFT, an implementation of the Liouville-Lanczos approach to linearized time-dependent density-functional theory, designed to simulate the optical spectra of molecular systems made of up to several hundred atoms. turboTDDFT is an open-source software distributed under the terms of the GPL as a component of Quantum ESPRESSO. As with other components, turboTDDFT is optimized to run on a variety of different platforms, from laptops to massively parallel architectures, using native mathematical libraries (LAPACK and FFTW) and a hierarchy of custom parallelization layers built on top of MPI.