Resale has moved from niche to mainstream, with over half (59%) of consumers shopping secondhand apparel last year, according to thredUP. But as platforms scale to millions of items, the real challenge shifts from inventory to discovery, helping shoppers navigate an endless aisle of one-of-a-kind pieces without feeling overwhelmed.

"We have about 4 million items on our site at any given time. We drop about 65,000 new items on our site every day," Kristen Brophy, senior vice president and head of marketing at thredUP, said on a recent episode of "Reimagining Retail.”

The company is tackling this complexity through AI-powered personalization that transforms how consumers find and buy secondhand fashion.

AI transforms merchandising into personalization

Traditional merchandising strategies don't work when every item is unique. ThredUP has reimagined merchandising as personalization, using AI to curate individual shopping experiences at scale.

The platform recently launched several AI-driven tools, including:

• Daily Edit: Recommends 100 personalized items daily based on browsing behavior and favorites
• Natural language search: Allows shoppers to search using phrases like "coastal cowgirl outfit for the next Beyoncé concert"
• Real-time personalization: Adjusts recommendations based on what shoppers click during their session

The technology addresses a fundamental tension in resale marketplaces. While some shoppers love browsing vast inventories, thredUP customers regularly scroll 10 to 20 pages deep, others need curation to avoid feeling overwhelmed. AI-powered personalization allows platforms to serve both audiences simultaneously.

"Personalization is really what becomes our version of merchandising," Brophy said. "Any woman can come shop on thredUP who has any type of personal style, and we can't really be one single aesthetic for one single type of personal style."

Resale requires rethinking brand values beyond sustainability

Brands entering resale often position it primarily around sustainability, but successful programs connect to broader consumer values, our analyst Sky Canaves noted.

"There's more to resale than just sustainability, which can be ‘a nice to have,’ but often isn't the most compelling factor from a consumer perspective," Canaves said.

Other compelling value propositions include:

• Pricing and value for budget-conscious shoppers
• Access to unique or discontinued pieces
• A gateway for new customers who may later buy full-price
• Community building among brand collectors

Brands should align resale programs with their specific brand identity rather than defaulting to sustainability messaging. This could mean emphasizing product longevity, serving size-changing customers (such as those using GLP-1 medications), or tapping into collector communities.

ThredUP uses lower-funnel marketing experiments to identify opportunities for upper-funnel brand campaigns, creating a feedback loop between performance and brand marketing.

• For example, a recent campaign around wedding guest dresses originated from paid social advertising on Meta, where event dress creative consistently outperformed other categories.
• This insight led to a comprehensive brand activation including a SoHo pop-up experience and the Pinterest-integrated "wedding dress guest decoder" tool, which curates dresses matching the mood of users' Pinterest boards.

"When you're pushing the boundaries in the lower funnel, you can actually inform some of your upper funnel storytelling," Brophy said.

Social platforms play a crucial role in resale discovery, according to thredUP's research. Video content particularly suits resale's single-SKU model, allowing detailed product showcases and storytelling around individual pieces.

Listen to the full episode

We prepared this article with the assistance of generative AI tools and stand behind its accuracy, quality, and originality.

This was originally featured in the Retail Daily newsletter. For more retail insights, statistics, and trends, subscribe here.