A joining device for producing an exhaust gas system for an internal combustion engine comprises a device base, a frame, and at least two joining units that can be operated simultaneously are fastened to the frame. The frame extends essentially vertically starting from the device base. In a method for producing the exhaust gas system, at least one joining unit of a joining device is oriented to a geometry of the exhaust gas system that is to be produced, at least three components or assemblies of the exhaust gas system are positioned in the joining device, and the components or assemblies are simultaneously connected.