EPSG.io allows to search in a global database of spatial reference systems, datums, ellipsoids and projections to identify transformation parameters required for a software to correctly handle the geographic location in a known coordinate system. This presentation shows various functions of the search system, and demonstrates how to use it efficiently to discover and identify the right coordinate system, transform the sample coordinates online, pick a position on a map, convert units, etc. It is possible to export definitions of coordinate systems in various formats, including WKT, OGC GML, XML, Proj.4, SQL or JS and directly use these in compatible systems such as Proj4JS and OpenLayers or PostGIS. The whole system is open-source with code on GitHub, and in the background it uses OSGeo Proj4 / OGR for all the transformations and it is powered by the latest EPSG Geodetic Parameter Registry released by IOGP regularly. The open-source tools used in backend could be used called on a command line in batch operations. Ideas for future improvement and cooperation with the community will be discussed.