EP Diagram is a teaching and learning tool for the analysis of electrocardiograms using ladder diagrams. Ladder diagrams are a classic method of analysing heart rhythms and conduction disturbances. The ladder is divided into anatomic regions and lines are drawn indicating conduction. EP Diagram goes much further than the traditional ladder diagram drawn by hand. Using it you can easily and quickly draw publication quality ladder diagrams which are interactive, scrollable, and zoomable. You can style these diagrams as you wish, have measurements, impulse origin, and block calculated automatically, and can edit and create your own ladders templates. You can even add periods of fibrillation with just one finger tap. Diagrams are automatically saved as files and can be shared with others. EP Diagram will improve your understanding of cardiac arrhythmias.