  The $\pi^0$, $\eta$, and $\eta^\prime$ transition form factors in the
space-like region are analyzed at low and intermediate energies in a
model-independent way through the use of rational approximants. Slope and
curvature parameters as well as their values at infinity are extracted from
experimental data. These results are suited for constraining hadronic models
such as the ones used for the hadronic light-by-light scattering piece of the
anomalous magnetic moment of the muon, and for the mixing parameters of the
$\eta - \eta^\prime$ system.
