The increasing number of surveys available at any wavelength is allowing the construction of Spectral Energy Distribution (SED) for any kind of astrophysical object. However, a) different surveys/instruments, in particular at X-ray, UV and MIR wavelength, have different positional accuracy and resolution and b) the surveys depth do not match each other. All this makes the pairing of sources among catalogs not trivial, specially in crowded fields. In order to overcome this issue, and in view of the launch of eROSITA, we released a new algorithm, NWAY, which combines the best of Bayesian and frequentist methods but that can be used as the common Likelihood Ratio (LR) technique in its simplest application. In this talk I will introduce the code and how it has been used with a simultaneous color-magnitude prior for finding the correct counter parts to various Xray surveys (e.g. ROSAT, XMM, SWIFT/BAT).