“The design should always keep users informed about what is going on, through appropriate feedback within a reasonable amount of time.” — Jakob Nielsen
Below are eight small, working demos. Each one deliberately violates this heuristic in a way that real products still ship with. Try interacting with each one as a first-time user would, before clicking “Reveal what actually happened” to see what the system was doing behind the scenes while you were left guessing.
Clicking “Save” gives no acknowledgement at all — no disabled state, no spinner, no message. There is nothing to tell you whether the click even registered, so the natural response is to click again. And again.
A spinner appears, which at least signals something is happening — but it never resolves into success, failure, or a timeout. There's no way to tell if it's still working, stuck, or safe to give up on.
The bar races to 99% in under a second, then freezes. It never tells you whether the last 1% will take another second or another hour — classic “stuck at 99%” behaviour.
Flip this switch a few times. About half the time the switch visually ignores your click, even though the underlying setting changes every single time. The visible state and the real state quietly drift apart.
Click “Delete” on an item. It is removed from the system immediately — but the list on screen never updates, shows no strikethrough, no toast, no undo. You have no way of knowing the action succeeded.
A multi-step checkout with no step counter, no progress bar, and no titled steps. You can fill in real fields and move forward and back, but you never know how many steps remain, how far you've come, or whether what you typed was even kept.
Fill in the form and submit it. If anything is wrong, the system refuses to continue — but only ever shows a generic “Submission failed” banner. It never says which field is the problem or what would fix it, so you're left guessing and resubmitting the same thing over and over.
Click the control below to turn “Auto-sync” on and off. It genuinely changes state every click — but the on and off appearances are so close in colour, with no label, icon, or moving part, that you can't reliably tell which state it's in just by looking.