0_5242 The detection of single photons in the microwave range is of great interest for many different applications, from quantum computing to the search for exotic particles such as Axions, possible candidates for cold dark matter. The latter objective is possible, for example, thanks to the conversion of a single Axion in one photon inside a cavity with a large static magnetic field (Primakoff effect). Superconducting systems based on Josephson junctions have proven to be effective in the hard task of detecting these low-energy photons. For example, they can be used as current-biased switching detectors or, in a more complex scheme, as Transmon qubits where the incident photon causes an excitation. We present a series of experimental tests in this direction, discussing obtained results, issues and perspectives.