We report on the first comparison of distant caesium fountain primary frequency standards (PFSs) via an optical fiber link. The fountains are FO1 and FO2 (Cs and Rb), at LNESYRTE in Paris and, CSF1 and CSF2 at PTB in Braunschweig. These fountains regularly contribute to the calibration of International Atomic Time (TAI) and have been utilized for a number of absolute measurements of optical clock transition frequencies. Benefiting from the phase coherent optical frequency transfer via a stabilized telecom fiber link, they are compared, for the first time, without uncertainty from the link. All fountains agree well within the combined comparison uncertainties of a few 10􀀀16, which fully supports their stated uncertainties. Besides, the comparisons yield a new precise absolute determination of the 87Rb ground state hyperfine transition frequency recognized as a secondary representation of the second.