Comparison of relatively unipotent log de Rham fundamental groups Summary: In this paper we prove compatibilities of various definitions of relatively unipotent log de Rham fundamental groups for certain proper log smooth integral morphisms of fine log schemes of characteristic zero. Our proofs are purely algebraic. As an application we give a purely algebraic calculation of the monodromy action on the unipotent log de Rham fundamental group of a stable log curve. As a corollary we give a purely algebraic proof to the transcendental part of Andreatta Iovita Kim’s article: obtaining in this way a complete algebraic criterion for good reduction for curves.