Abstract: In this talk, I will first introduce how to measure dark energy in cosmology, then focus on galaxy surveys. Galaxy surveys provide us with maps of the cosmic density field. The statistical properties of the density field are tightly connected to the cosmological evolution and the amounts of dark energy, dark matter, etc. I will also show how it is possible to measure the radial peculiar velocities of galaxies in the nearby Universe, increasing the precision on cosmological constraints relative to density-only constraints. The DESI Peculiar Velocity survey released its first measurements in Dec 2025. I will highlight some key aspects of this analysis that make it robust. Finally, I will give some highlights on similar work being developed in CPPM with supernova surveys such as ZTF and LSST.