What eight fintech systems taught me about simplicity

Almost everything I have designed in the last few years is fintech. Brokerage onboarding, an options terminal, a premium bank, crypto options. I am Alexander Chernov, and these are systems that push back against simplicity: behind every screen there is regulation, risk and math you do not get to hide just because it frightens people.

Four rules survived all eight projects.

1. Simplicity is measured in decisions#

A trading terminal does not get simpler when you delete half the data. It gets dangerous. Simplicity is the number of decisions a person has to make before they get a result. Twenty dense tables on one screen are fine when there is one obvious path through them. Three buttons are bad when nobody can tell which one is theirs.

2. Trust is drawn in the details#

In finance the interface is the storefront of a vault. People hand money to whatever feels orderly. Figures aligned on the decimal separator. Tabular numerals instead of proportional ones. Row heights that match. Loading states that hold still. Nobody notices any of this on purpose. Everybody uses it anyway: the place looks careful, so the money is probably handled carefully too. I cannot prove this rule. There is no A/B test where the only variable is tabular numerals, and I have never run one.

3. The worst case is the main case#

Anyone can design the happy path. A system shows its character on a bad day: a margin call, a rejected transfer, a portfolio in the red. A product that talks about bad news clearly, without bureaucratic language and without panic, gets forgiven almost anything else. So I start with the bad news. The loss screen matters more than the profit screen, because that is where a person decides whether to stay with you.

4. Complexity has an address#

In any system complexity lives somewhere. In the user’s head, in the interface, or in the backend. It never disappears. It moves. My job is to move it down the stack: whatever can be calculated for the user gets calculated, whatever can go unasked stays unasked. Every field in a form is complexity somebody was too lazy to move.

An interface that explains the system is a good interface. An interface that apologizes for the system means the system has to change.

All eight, with pictures, are in the portfolio, from the space blue of ATON Space to the dark terminal of OptionStream.