A living data collection providing critical chloride contents for steel corrosion in concrete (C) is presented. The C values were measured on samples taken from engineering structures. This approach allows to overcome the well-known limitations of testing laboratory samples. The data are available in a public data repository. Currently, 46 C are reported (measured on four different structures). The database will continuously be updated. The database includes information about the structure, material properties, and local condition of the steel-concrete interface. For possible applications of this database and discussion refer to the related research article in Corrosion Science.