The paper deals with the issues of cross-identification of sources from various astronomical catalogs. One of the main problems under consideration is how to cross-identify a large number of catalogs in a selected region in the sky when there is no reference source catalog? For cross-identification of large amounts of data, it is proposed to use the DBSCAN group search algorithm. A special program code "cross-match.online" has been developed, which works in online and offline modes, which allows you to automate the process of cross-identification of sources across a variety of catalogs. The paper deals with the issues of comparing catalogs with different source densities, resolving uncertainties in cross-identification, and also taking into account the uncertainty of source positions. A technique is proposed that makes it possible to cross-identify catalogs with different source densities and different position uncertainty values. Open access to the system is provided at https://cross-match.online.