This Technial Guideline specifies the eID-Client software for Online-Authentication based on Extended Access Control Version 2 (EAC2) between an eService and an eID-Card, e.g. the German eID-Card or the German electronic Residence Permit. The eID-Client implements the client side of this authentication. The server side is implemented by the eID-Server, see [TR-03130], part 1.