Donghyun Kang.

AI Product Engineer

Jaemiro Rewarded Ad Platform | Donghyun Kang | Donghyun Kang

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★ Case 07 / 7Product Engineer Donghyun Kang

Jaemiro Rewarded Ad Platform

"See for yourself" instead of "trust us" — trust was a structure, not a promise.

외주 턴키Full-Stack2024.04 ~ 2024.07

Google Play

01.Discover

The real problem with sweepstakes apps was the trust gap.

The reward did pull engagement in. Watch the ad, enter the draw, win the prize — a simple structure. But when I looked at early-launch user reactions, doubt followed every entry — "Is the prize real?", "Are they just harvesting my info?", "Is this just an ad and nothing else?" The bigger the reward, the bigger the doubt.

The answer was not to plaster "you really do win" in bigger type. Stronger promises only deepened the doubt. Trust only built on top of *a structure the user could see for themselves*. Carrying this from planning to launch as PO taught me that one thing.

Field notes

Note 01

"Is the prize real?"

Even with the prize visible, if the drawing was hidden, users had no way to verify that the win was real.

Note 02

"Are they just harvesting my info?"

Every time the entry form asked for data, the user wondered: "why are they collecting this?"

Note 03

"Is this just an ad and nothing else?"

After watching the ad, if the connection from entry to reward was not visible, users felt like the ad used them and the experience ended.

02.Build with AI

Designed trust as structure, not as copy.

Decision 01

Live entry status

The answer to "is the prize real?" was letting users watch the drawing actually happen. Surfaced entry status in real time so users could see exactly where their own entry landed.

BeforeThe drawing process was a black box

AfterEntry counts and your own position shown in real time

tradeoffExposing data vs. making trust visible

Decision 02

Winner announcements + verification photos

Verification photos made the existence of winners visible. "There really are winners" became visible proof, which pulled the next round of entries in. As a side effect, the photos themselves became marketing assets.

Decision 03

An experience that closes at delivery

Folded ad → entry → win → shipping into one flow inside the system. Blocked the "ad only" doubt structurally — showed in one continuous flow that entries lead to a real delivery.

Decision 04

"Trust us" → "See for yourself" copy policy

Stripped the promise-style copy ("you really do win") off the page and replaced it with data the user could verify directly. Trust came from how verifiable it was, not from how loud the promise was.

03.Prove with metrics

Trust came back as engagement.

Ad engagement rate

20%+

Reached during the early launch period

Marketing asset

Winner verification photos

Naturally user-generated content

Copy policy

"Trust us" → "See for yourself"

Verifiability instead of a promise

Ownership

3 months, 3-person team, PO

Solo ownership from planning to launch

What this case is really about

“Design around rewards alone and engagement shows up; trust does not.”

Discover

Named the real problem behind sweepstakes-app engagement: the doubt that follows every entry — a trust gap.

Build

Built trust as UX structure rather than copy: live entry counts, winner verification, shipping receipts, and a copy policy that swaps promises for proof.

Prove

Ad engagement above 20%; winner photos became marketing assets on their own — solo PO + full-stack ownership.

Linked principlesUser-FirstTrust-by-Design

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