Context :

Aims : We present the first public release of photometric redshifts , galaxy rest-frame properties and associated magnification values in the cluster and parallel pointings of the first two Frontier Fields , Abell-2744 and MACS-J0416 .
The released catalogues aim at providing a reference for future investigations of the extragalactic populations in these legacy fields : from lensed high-redshift galaxies to cluster members themselves .

Methods : We exploit a multi-wavelength catalogue ranging from HST to ground-based K and Spitzer IRAC which is specifically designed to enable detection and measurement of accurate fluxes in crowded cluster regions .
The multi-band information is used to derive photometric redshifts and physical properties of sources detected either in the H-band image alone or from a stack of four WFC3 bands .
To minimize systematics median photometric redshifts are assembled from six different approaches to photo-z estimates .
Their reliability is assessed through a comparison with available spectroscopic samples .
State of the art lensing models are used to derive magnification values on an object-by-object basis by taking into account sources positions and redshifts .

Results : We show that photometric redshifts reach a remarkable \sim 3-5 % accuracy .
After accounting for magnification the H band number counts are found in agreement at bright magnitudes with number counts from the CANDELS fields , while extending the presently available samples to galaxies intrinsically as faint as H160 \sim 32-33 thanks to strong gravitational lensing .
The Frontier Fields allow to probe the galaxy stellar mass distribution at 0.5-1.5 dex lower masses , depending on magnification , with respect to extragalactic wide fields , including sources at M _ { star } \sim 10 ^ { 7 } - 10 ^ { 8 } M _ { \odot } at z > 5 .
Similarly , they allow the detection of objects with intrinsic SFRs > 1dex lower than in the CANDELS fields reaching 0.1-1 M _ { \odot } / yr at z \sim 6-10 .

Conclusions :