The Phia App: Everything You Need To Know About Phoebe Gates and Sophia Kianni Shopping Start-Up

Move over Depop and eBay, there’s a new kid on the resale block — and it’s techier, savvier, and designed by two seriously impressive Stanford grads. Meet Phia, the browser extension and iOS app aiming to make secondhand shopping as easy as booking a flight.

Dubbed the “Google Flights for fashion” by co-founder Sophia Kianni, Phia helps users decide whether to buy an item new or pre-loved, by pulling together massive amounts of resale data. Eyeing that dreamy white designer dress for £200? Phia will tell you if you can find it secondhand for £150 instead. Not just vibes — actual data.

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With access to a whopping 250 million secondhand listings across 40,000 sites, Phia isn’t just guessing. Tap the “Should I Buy This?” button while shopping and you’ll get an instant price comparison. The app is free to use, and Phia earns its keep through affiliate links when users snap up their finds.

Behind this slick piece of shopping tech are two heavyweights: Sophia Kianni, a Forbes 30 Under 30 climate activist and UN advisor, and Phoebe Gates, yes, daughter of that Bill Gates. Together, they spotted the secondhand shopping gap while bonding as roommates at Stanford. “We both loved secondhand shopping, but found it so difficult to compare across different websites,” Kianni said. Enter: the idea for Phia.

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Secondhand fashion isn’t just a TikTok aesthetic anymore; it’s a booming market. ThredUp’s 2024 report showed U.S. secondhand apparel sales grew 14%, and the sector’s set to hit $74 billion by 2029. With potential new tariffs making fresh fashion even pricier, more consumers (59%, to be exact) are planning to go preloved.

As Gates put it: “People don’t care about the resale value itself. What they care about is feeling justified in their purchase and knowing whether they should buy this item new, or secondhand.”

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Phia isn’t flying solo either. Kris Jenner is among the early investors, and Gates and Kianni have launched a podcast, “The Burnouts”, sharing the wild ride of startup life. Unlike polished business podcasts of yore, “The Burnouts” captures entrepreneurship in real-time, with plenty of honest chat about wins, fails, and learning curves.

As Gates says: “We’re still in it and learning how to do things and making mistakes… and we want to pull back the curtain even more.”

So next time you’re torn between add to cart or hunt for a deal, Phia might just be your new shopping BFF — and your wallet (and the planet) will thank you.