Poshmark co-founder Tracy Sun looks back on 2011, the year she and Manish Chandra launched their company, as if it was a different era.

“Instagram had just launched, no one really said ‘selfie,’” said Sun. “Not everyone owned a smartphone yet and people weren’t using them for everything they are today.”

Still, Sun and Chandra made a bet on mobile-only social commerce, a business model for its network of individual seller boutiques, where users can sell used and wholesale items. The business has expanded from a mobile reselling platform to a place where sellers can launch their own brands, or become wholesale partners on behalf of brands. As it’s expanded, it’s remained mobile-only.

Sun joined the Glossy Podcast to discuss the brand’s natural evolution from mobile to social commerce, and how it’s convincing brands to believe in the new social seller class.

On being mobile only
Sun said Poshmark’s original goal was to be the go-to app for people to shop and sell on their phones. The team saw a potential for shopping and selling to become a social-driven experience based on personal connections, and those were already happening on mobile. And as a startup, it didn’t have much of a choice other than to keep its focus narrow in the early days.

“It’s hard to launch a mobile experience as an add-on,” she said. “It’s hard to put in the resources otherwise. For us, mobile is everything — we had to do it. We knew that we had to do one thing well and really own it, and that was mobile.”

Spinning mobile commerce into social commerce
Behind a mobile shopping platform, Poshmark’s early goal was to build a social network out of its network of buyers and sellers. She said that the two — mobile and social — go hand-in-hand, because the majority of our time spent on our phones is based on the emotional connection that comes with checking in with people, whether that’s on Instagram or via text message. That doesn’t happen on a typical mobile shopping app, but users check back in on Poshmark between seven and 10 times per day.

“If you think about what we do on our phones, we text, check Facebook, take photos, look at Instagram. We’re connecting with people,” she said. “Our decision to remain mobile-only was based on the idea that we wanted to connect people with others.”

Introducing brands to a “new selling force”
Brands can work directly with Poshmark sellers to supply them with new, unused inventory, but some brands shy away from the idea of “user-generated selling,” as Sun called it. It’s putting a lot of control into the hands of individual sellers. Sun said Poshmark is taking an “if you build it, brands will come” approach.

“There’s a lot going on in the industry that’s scaring brands, and something needs to change,” she said. “We’re building our business with brands that are into this idea of a new selling force. Luxury brands in particular are having a hard time with it, but they’re watching the space to figure out how it fits into their strategy.”