MAP syntax diagrams is an online R Shiny application for studying Ancient divine onomastic sequences. It uses the format defined by the “Mapping Ancient Polytheisms” (MAP) project to: 1) represent sequences and 2) describe semantic relationships between the parts of these sequences (called “elements” in the MAP terminology). The focus is on the structure of the sequences, not their content. These structures are modelled as graphs (a mathematical object composed by a set of nodes and a set of edges), so that they can be visualised, characterised, and compared using quantitative measurements.