Why we built our POS for cashiers, not engineers

The POS purchase decision is usually made by the owner, but a cashier uses that screen eight hours a day. The gap between purchase criteria and usage criteria explains most of the bad POS experience in this industry.

Design rules change during the rush

• Targets have to be large — a tired, hurried finger does not tap precisely.
• Confirmation dialogs belong only on irreversible actions; unnecessary confirmation breeds blindness.
• Colour alone must not carry information; low contrast is unreadable under kitchen lighting.
• Undoing a mistap has to take one step.
• No critical flow should require scrolling.

Features we removed

Some of the decisions that improved the product were subtractions, not additions. We took the detailed product description, the stock-level indicator and the customer-history panel off the cashier screen. All three were useful information — and all three were noise during the rush. They all still live on the manager screen.

What we measured