  Context. Clusters of galaxies are important for cosmology and astrophysics.
They may be discovered through either the summed optical/IR radiation
originating from their member galaxies or via X-ray emission originating from
the hot intracluster medium. X- ray samples are not affected by projection
effects but a redshift determination typically needs optical and infrared
follow-up to then infer X-ray temperatures and luminosities. Aims. We want to
confirm serendipitously discovered X-ray emitting cluster candidates and
measure their cosmological redshift through the analysis and exploration of
multi-wavelength photometric catalogues. Methods. We developed a tool, the
Integrated Cluster Finder (ICF), to search for clusters by determining
overdensities of potential member galaxies in optical and infrared catalogues.
Based on a spectroscopic meta-catalogue we calibrated colour-redshift relations
that combine optical (SDSS) and IR data (UKIDSS, WISE). The tool is used to
quantify the overdensity of galaxies against the background via a modified
redMaPPer technique and to quantify the confidence of a cluster detection.
Results. Cluster finding results are compared to reference catalogues found in
the literature. The results agree to within 95-98%. The tool is used to confirm
488 out of 830 cluster candidates drawn from 3XMMe in the footprint of the SDSS
and CFHT catalogues. Conclusions. The ICF is a flexible and highly efficient
tool to search for galaxy clusters in multiple catalogues and is freely
available to the community. It may be used to identify the cluster content in
future X-ray catalogues from XMM-Newton and eventually from eROSITA.
