The electron-phonon interaction is ubiquitous in many-particle physics and chemistry. The strength of the electron-phonon coupling (EPC) determines countless physical properties and phenomena. Notably, it gives rise to conventional superconductivity and plays a key role in high-temperature superconductivity. The main goal of RENOIR is to accurately determine the EPC strength in materials that are relevant for technological applications, providing crucial insights into the behaviour of excitons and phonon-driven phenomena. Resonant inelastic x-ray scattering (RIXS) spectroscopy holds the promise to access phonon excitations with a remarkable high-resolution, thanks to the significant technical advancements achieved in recent years, providing momentum dependence and bulk sensitivity. However, the interpretation of measured signatures remains challenging since different excitations are coupled through interactions. Indeed, although RIXS is used to measure EPC, it primarily reveals exciton-phonon coupling, due to the interaction with a core hole. So far, theoretical approaches mainly rely on oversimplified models that use adjustable parameters to fit experimental results, limiting their applicability. RENOIR aims to convert this challenge into the opportunity to realise the great potential of RIXS to determine EPC in quantum materials. RENOIR will develop a novel parameter-free methodology to calculate RIXS spectra, combining accurate and reliable approaches, such as the Bethe-Salpeter Equation within Green’s functions theory for excitons, and Density Functional Perturbation Theory for phonons. As a primary application, RENOIR will focus on high-temperature superconducting materials and heterostructures, celebrated for their transformative power in electronics and energy applications. Moreover, the resulting software will be made freely available to a very wide community, opening the way for understanding and predicting RIXS measurements of EPC in many other materials