The main motivation for the FingerprintAZO project is to investigate the photochemistry of the isomerization reaction of substituted and unsubstituted Azo molecular system in different energy levels: the excited states S2 and S1 and the ground state S0, including the fingerprints of chemical species taking into account the electronic state configurations and spectral properties along the trans ↔ cis conversion. In detail, the complex interplay between electronic density and conformational effect in ground and into excited state will be presented. This methodology can be applied to obtain the adequate spectral fingerprints of the transient species with different electronic configurations and structures. Putting all data into a representative library of molecules permits us to create and to provide such design rulebook to extract and to elucidate the direction of isomerization along with the potential topology. The utilization of this molecular fingerprint permits us to find new the transition states in isomerization process along the forward and backward trans-cis reaction of azobenzene derivatives and also being carefully controlled.