Secondhand Superstars

The Challenge

In 2023, Mercari, a resale marketplace, faced a unique conundrum: while its Japanese user base logged in daily, its 23 million US users averaged only one or two sessions a week. This disparity wasn’t just a metric—it was a wake-up call. With only 80,000 daily active users in the US, Mercari’s potential for engagement was falling short. The task was clear: discover what drives deeper connections for US users and turn insights into impactful changes.

My Role

As the lead researcher on this project, I set out to uncover the habits, motivations, and needs of Mercari’s most active US users. By combining data analysis, user storytelling, and strategic collaboration, I aimed to align Mercari’s marketing and product development with the heart of its community. I didn’t just want to study the “secondhand superstars”—I wanted to unite cross-functional teams across the company around our most engaged customers' needs.

The Research Process

Finding the Stars

The first step was to identify the most engaged users—those active for 60+ days in the past quarter—and understand who they were. Through surveys, we segmented them by lifetime value and whether they were buyers, sellers, or both. These surveys revealed more than numbers; they surfaced patterns of behavior, motivations, and frustrations.

A Week in Their Shoes

To dig deeper, I designed a diary study. For seven days, selected participants documented their every resale-related interaction. The setup was intentionally lean—a simple system of Google Drive and daily surveys—but the insights were profound. From snapping photos of transactions to reflecting on their motivations, participants painted a vivid picture of their experiences.

Voices Behind the Clicks

The diaries led to 60-minute follow-up interviews. These conversations, open to stakeholder observation, became pivotal moments for alignment. Through them, we uncovered the “why” behind the “what,” transforming data points into human stories.

Synthesizing the Story

Using EnjoyHQ and affinity mapping, I coded themes, identified patterns, and built highlight reels that amplified user voices. These weren’t just findings—they were a call to action.

Key Insights

Everyday Sellers Create Everyday Magic

"What I love about Mercari is the naivete"
The majority of the platform's sellers weren’t professionals—they were casual users listing items for fun or extra cash. Their occasional pricing mistakes created a “thrill of the hunt” for buyers, fueling engagement. Features like saved searches and offers were crucial enablers.

Purposeful Connections Matter

“I don’t want to feel like I have to be besties with everyone on the internet”
Users weren’t looking for a social network; they wanted meaningful, commerce-driven interactions. Thoughtful touches, like thank-you notes in packages, added authenticity and trust. This was a difficult finding to deliver given a strong organizational push to incorporate more social features.

Reputation Reinforces Engagement

In addition to the thrill of the hunt or the rush of a sale, for both buyers and sellers, ratings and messages weren’t just functional—they were relational. These tools built trust, reinforced by small gestures of gratitude.

From Insights to Action

I modeled the behaviors I observed from participants in the diary study using the Hook Model of Habit Formation.

With these insights, the team and I set out to transform Mercari's product roadmap.

Workshopping Solutions

Through collaborative workshops, we bridged the gap between user needs and product opportunities. Leaders from UX, product management, and marketing joined forces to brainstorm solutions rooted in user behaviors.

Challenges Along the Way

• Balancing Statistical Rigor and Storytelling. Studying extreme user groups required creative metrics to measure sustained engagement without oversimplifying the data.
• Mitigating Observation Bias. Awareness of the study sometimes influenced user behavior. By analyzing app interactions before and during the study, I worked to separate genuine behaviors from “performance.”
• Resourceful Research. With limited tools, I relied on scrappy methods (like Google drive and daily in-app survey reminders) to ensure both accessibility and rigor in data collection and synthesis.

The Results

• Strategic Impact. Insights influenced Mercari’s product roadmap, with features like saved searches receiving dedicated resources to boost habit formation.
• Marketing Evolution. AppStore positioning and campaigns shifted to highlight what users valued most.
• Executive Alignment. When the study was rolled out, leadership conversations began to focus less on personal assumptions of what our most engaged users needed, and instead focused on users' "jobs to be done."
• Organizational Empathy. From engineers to executives, Mercari’s teams connected more deeply with the human stories behind their work.

What they're saying

Megan led one of the most important studies in the product team’s history, helping us understand who our core user base is, what their motivations are and what their key pain points are. This study is still essential to how we think about our customer base and product today.

Looking Back

This project was more than a research study—it was a lesson in the power of user-centered design to drive strategic transformation. It taught me how to navigate resource constraints, rally cross-functional teams, and advocate for the user at every level. Ultimately, it wasn’t just about engagement metrics—it was about creating a platform that resonates with the people who use it.