On almost inner derivations of Leibniz algebras

We introduce the notion of almost inner derivations in Leibniz algebras as a generalization of the inner derivations defined by Boyle, Misra, and Stitzinger. We then study their key properties and determine the Lie algebra of inner derivations and almost inner derivations for all non-Lie nilpotent Leibniz algebras of dimension at most 4, providing new insights into the relationship between algebraic structures and derivations.