Post-Purchase Offers
I designed and launched PayByPhone's first third-party ad product. The challenge was monetizing without disrupting the app's fast parking flow, solved through research and live A/B testing.
Role
· Product Design Lead
Team
· 1 PM, 3 Devs, 1 Financial Analyst
Duration
· 6 months
Year
· 2024
49%
higher revenue from the winning placement
$1.5M
projected annual run rate within six months
100K
monthly users engaging with offers
Challenge
Capturing a high-value moment without breaking trust
PayByPhone wanted to unlock a new revenue stream from the most engaged moment in the app: right after someone finishes paying for parking.
The opportunity was to surface relevant partner offers at a high-intent moment. The difficulty was doing it without eroding trust in the app's primary job. Anything that felt like an ad blocking the parking task would undermine the utility people rely on, so the feature had to stay optional, well timed, and easy to ignore.
How might we
…design a seamless, optional way to present offers without disrupting the parking experience for users?
Validation
Two methods to choose the right placement
I paired qualitative depth with quantitative scale to settle the placement decision with evidence rather than opinion, testing the two concepts against the conflicting goals of visibility and low friction.
QUAL · User interviews
Moderated interviews showed a clear preference for the embedded offer. Users said it reassured them their parking was finalized before any offer appeared. The overlay read as a mandatory barrier that broke the non-intrusive feel.
QUANT · Usability test
A larger unmoderated study used the overlay as a control to measure impact at scale. Task times confirmed the overlay added overhead, while every tested design still scored in the excellent usability range.
Verdict: the embedded placement was confirmed as the foundation for the product.
Explorations
Two decisions that shaped the offer
I explored concepts against the tension at the heart of the product, maximizing revenue while minimizing friction, then let the research pick the winners.
Decision 1 · Offer placement
Overlay offer
✗ Rejected
Forced an interaction, read as a barrier
Embedded offer
✓ Selected
Decision 2 · Progress indicator
The Rokt platform could not let users return to an offer once seen, so swipeable carousels were ruled out. I explored ways to signal forward-only progress.
Numeric 1 of 3
✗ Rejected
Did not signal you cannot go back
Three-circle tracker
✓ Selected
Final designs with new design system
An embedded offer that respects the flow
The shipped design places the offer under the active session card once parking is paid, uses the three-circle tracker for multi-offer sets, and was later brought fully in line with the updated design system.
Embedded offer under the active session
Multi-offer flow with the progress tracker
Refined to the new design system
Plot twist
Lab tests proved comfort, not conversion
Usability testing told us the design felt effortless. It could not tell us whether people would actually tap an offer, so I took the decisions live.
The measurement gap
Usability scores measure friction. Revenue depends on real tapping behavior, which only live traffic reveals.
The response
I ran two live A/B experiments to capture conversion data on the elements most likely to move revenue.
EXPERIMENT 1: CTA PLACEMENT
Stacked vs side-by-side buttons
I tested a space-saving side-by-side layout against the standard stacked layout to see which gave the CTA more tapping ease and prominence.
Control: Stacked - Winner
Variant: Side-by-side
49%
higher revenue impact from the stacked CTA
EXPERIMENT 2: PROGRESS TRACKER
With vs without the tracker
I tested whether revealing the full offer count on the first screen would build engagement through transparency or add friction.
Control: With tracker - Winner
Variant: Without tracker
1.9%
revenue lift from showing the progress tracker
Results and celebrations
Monetization that earned its place in the flow
The embedded placement, stacked CTA, and progress tracker delivered verifiable success across business and user metrics, proving that high-impact monetization can layer into a core utility flow.
$1.5M
projected annual run rate in under six months
100K
monthly users engaging with offers
49%
revenue lift from the winning placement
Met
reached the Rokt engagement benchmark in North America
Reflection
What I carry forward
Monetization can live inside a core utility flow when it stays optional, lands at a high-intent moment, and is validated with both lab and live data. The biggest unlock was treating usability and conversion as separate questions: comfort in testing did not guarantee tapping behavior, and only live experiments told the full story.