Thread by @DenisJeliazkov

Look at these 2 UIs.

One of them will 100% outperform the other for one reason:

Peak-End Rule.

Here's how this psychological principle works & how to use it in your products:

As the name suggests, this rule states that your users don't remember everything about your app.

They only remember two things:

1. The most intense moment (peak)
2. How it Ends

That's it. The rest is forgotten by their brain.

(Credits: @UXChrisNguyen)

What this essentially means is that you can literally have 20 mediocre screens...

But if you nail the peak & end?

Users will still love your product. (not saying you intentionally make it mediocre lol)

Let me show you who's doing this right (and who's f*cking it up):

Apps crushing the Peak-End Rule:

1. @DUOLINGO

Peak: Those addictive animations when you get answers right
End: Cheerful celebration + clear progress

Your brain literally gets a dopamine hit.

No wonder people are addicted...

2. @UBER

They turned waiting (negative peak) into tracking your driver in real-time.

Then, when your ride arrives...

You're hit with a notification.

Interesting way to transform anxiety into anticipation.

Now here's who's screwing it up:

1. BANKING APPS

Complex steps → frustrating peak
"Success" screen → boring end

You just moved $10k, and all you get is... "Transaction complete"?

Bro, jazz it up a little.

2. CUSTOMER SUPPORT CHATS

Long wait = negative peak
"Case closed" = abrupt end

Doesn't matter if they solved your problem.
You end up remembering the pain instead of the solution.

3. TICKETING SITES

Surprise fees at checkout = rage peak
Basic confirmation = forgettable end

They had you excited for a moment.
Then killed it with a $30 "convenience fee."

Now you hate them forever.

So how do you use this? Very simple:

Map your user journey.
Find the most emotional moments.
Make them memorable (for good reasons).

Then look at your endings:

• Success states
• Confirmations
• Final screens

And turn them into celebrations.

The best part is that this rule is not limited to just apps.

It applies in different facets of business as well:

Sales calls: Nail the demo (peak) and follow-up (end).
Client work: Smooth kickoff, amazing delivery.
Presentations: Strong opening, killer close.

TL; DR:

People forget the middle.

They remember how you made them feel.

So stop obsessing over perfecting every pixel.
And start obsessing over your peaks and endings.

Because that's all your users will remember anyway.

Founders:

We've helped 60+ startups ship beautiful products that actually convert.

So if you’re looking for a metrics-driven, world-class UX/UI for your app/product with no fluff...

Book a call and let’s see how we can help:
cal.com/denisjeliazkov…

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