The present invention provides a branched, a dendritic, or a hyperbranched poly(amino ester) having a polymer backbone comprising a plurality of branches, wherein the polymer backbone has at least one secondary and at least one tertiary amine linkage. Branched poly(amino ester)s are prepared via a Michael addition reaction of a tris(acrylate ester)monomer with a diamine monomer. In one aspect, the diamine monomer has a primary amino group and a secondary amino group. The poly(amino ester) compounds can be end-capped by reacting with a suitable agent. The present invention also provides applications including, but are not limited to, the delivery of bioactive agents, such as drugs, DNA or RNA; or biocompatible imaging.