Excalidraw

Minimal Excalidraw JSON — two rectangles and an arrow, sketchy rough-pen rendering.

Diamond + two outcomes — the kind of figure that lives in a half-finished whiteboard photo.

A hand-drawn retrospective wall with three column headers and nine sticky notes for a software team's sprint review — what to start, stop and continue — and the dot-vote instruction underneath. Every note is a bound label inside its rectangle, so dragging a sticky in Excalidraw carries its text with it.

The architecture a team draws on a whiteboard before writing the design doc: mobile app through an API gateway to the orders and payments services, the orders database, the external card processor behind 3-D Secure, and an order.placed event feeding the email worker — with the open question about idempotency keys pencilled beside it.

A sketched experiment plan for a checkout redesign: eligible visitors, a 50/50 randomisation, control and variant arms and the primary metric, with the pre-registered numbers underneath — a 3.2% baseline, a 0.4-point minimum detectable effect, α 0.05 and 80% power, which needs about 32,000 visitors per arm. Illustrative values.

The timeline a post-mortem starts from, drawn on a whiteboard: from the deploy that shrank the database connection pool at 13:02 to recovery at 13:51, with the alert, page, diagnosis and rollback in between and the phase durations underneath — 7, 5, 17 and 20 minutes, adding to 49 minutes of customer impact. Illustrative values.