  We employ a systematic and model-independent method to extract, from space-
and time-like data, the $\eta$ and $\eta'$ transition form factors (TFFs)
obtaining the most precise determination for their low-energy parameters and
discuss the $\Gamma_{\eta\rightarrow\gamma\gamma}$ impact on them. Using TFF
data alone, we also extract the $\eta-\eta'$ mixing parameters, which are
compatible to those obtained from more sophisticated and input-demanding
procedures.
