  We evaluate the leading-order QED radiative corrections to the timelike
Compton scattering (TCS) process $\gamma p \to l^- l^+ p$. We study these
corrections in two energy regimes using different models for the TCS amplitude.
In the low-energy regime we calculate the contribution due to the proton and
its lowest-energy excitation, the $\Delta(1232)$ resonance. In the high-energy
near-forward kinematical regime we calculate the TCS amplitude in a handbag
approach in terms of Generalized Parton Distributions (GPDs). On the level of
cross sections we find the QED radiative corrections to be in the $5 -10\%$
range in the low-energy regime and around $20\%$ in the high-energy regime. We
show that in both the di-lepton forward-backward asymmetry as well as in the
photon beam helicity asymmetry these corrections nearly cancel out, making them
gold-plated observables to extract the real and imaginary parts of the TCS
amplitude. We demonstrate in particular the sensitivity of these asymmetries on
GPD parameterizations for a recent CLAS12@JLab TCS experiment.
