ECG Builder draws the tracing you need.
Describe it the way you would say it to a colleague. "Inferior STEMI at 52 with reciprocal change." "Atrial fibrillation with RVR at 140." "LBBB with a paced rhythm." The sheet writes itself onto real millimetre paper, left to right, the way a recorder does.
Or build it by hand. Nine tools, each answering one question: what the rhythm is, how fast it runs, how the intervals measure, how it conducts, whether there is injury current, how it repolarises, whether the chambers are enlarged, whether there are extra beats, and whether it is paced.
WHY THE TRACINGS HOLD UP
Every tracing comes out of a physiologic model rather than a library of pictures, so nothing is pasted together.
Put ST elevation in the inferior leads and the reciprocal depression appears in aVL by itself, because the injury current is a vector and the leads facing away from it record the mirror image. Drag the rate under 60 and sinus rhythm relabels itself as sinus bradycardia. Pace the ventricle and the spike is projected onto all twelve leads from a single dipole, so its polarity is right in every one.
THE PAPER IS REAL PAPER
25 mm/s and 10 mm/mV mean what they say. Hold a ruler to the screen and the intervals measure correctly. Five layouts, including the international 3x4 with a rhythm strip and a stacked layout built for a phone so every lead stays legible without zooming. Four papers, from thermal cream to a defibrillator monitor.
A patient header prints above the grid the way a machine does: name, age, sex, rate, rhythm, date and time. All of it yours to set, and all of it fictional.
FOR PEOPLE WHO TEACH
Export a sheet as a PNG for a slide, or as a vector PDF at true physical size so a printed handout can still be measured with a ruler. Tracings you make are yours to use in slides, handouts, exams and question banks, including commercially.
Built for nurses and nursing students, paramedics and EMTs, medical students, ACLS and PALS instructors, and cardiology and critical care educators — anyone who needs one specific EKG and cannot find it.
WHAT IS FREE
Free builds a normal twelve-lead, and it can show you any other one. Ask for torsades de pointes and you get torsades de pointes, drawn in full, as a watermarked preview you can read but not edit or export.
ECG Builder Pro is one purchase and not a subscription. It unlocks every rhythm and every finding to edit, lets you roll a new patient with the same diagnosis, and lets the sheet leave the app clean.
WORKS OFFLINE, COLLECTS NOTHING
No account, no sign-in, and no network access at all. Every tracing is generated on your own device, including in Airplane Mode. The app collects no data of any kind.
EDUCATIONAL USE ONLY
Every tracing is synthetic, generated by a mathematical model, and never recorded from a person. ECG Builder is not a medical device and must not be used for diagnosis, treatment, or any patient-care decision.
ECG Builder is a CardioLens product.
Draw any 12-lead ECG or EKG from plain words. True paper scale, PNG and PDF.