Evolution of the H I photoionization rate in ionized gas (thick blue line) and the contributions of stellar populations (thick orange dashed line) and AGN (thick green dotted line), compared to the models of Haardt & Madau (2012) (thin dotted blue and dash-dotted green lines) as well as the constraints from the homogenized sample of Kulkarni et al. (2019) extending the AGN UV luminosity functon down to M₁₄₅₀ = −18 and other measurements (see text for details). Blue, orange and green labels correspond to the total photoionization rate, the stellar, and the AGN contribution, respectively. At z ≳ 4, and in particular during the whole EoR, the H I photoionization rate is completely dominated by the contribution of stellar populations.