Two Stanford roommates just unveiled an AI shopping assistant that's already tracking 350 million items across 150 second-hand platforms. Phia, co-founded by Phoebe Gates (yes, Bill's daughter) and Sophia Kianni, launched publicly after proving demand in beta, targeting the billion-dollar gap between online shopping chaos and personalized recommendations.
When Phia took the stage at TechCrunch Disrupt 2025 yesterday, co-founders Phoebe Gates and Sophia Kianni weren't just pitching another shopping app - they were unveiling what could become the personal shopper in everyone's pocket. The Stanford roommate duo has built an AI assistant that's already cataloging over 350 million items across more than 150 second-hand platforms, betting that sustainable shopping and smart recommendations can reshape e-commerce.
"There felt like there was this giant white space for, like, what should we actually buy, and why doesn't everyone have a personal shopper in their pocket?" Gates told the Disrupt audience, according to TechCrunch's coverage. The observation came after countless hours spent hunting for the right wardrobe pieces - a pain point that sparked their Stanford class project and eventually evolved into a full startup.
The Phia browser extension and mobile app goes beyond basic price comparison by integrating sustainability metrics directly into the shopping experience. Kianni emphasized that buying second-hand represents an 80% reduction in carbon footprint compared to new purchases, while typically offering significant cost savings. But the real innovation lies in Phia's AI-powered value predictions.
"If you're looking at a $500 handbag on Phia, you can quickly understand, can you resell that item for $300 or $400?" Kianni explained during their presentation. "Or, on the contrary, if it's a fast-fashion piece and you're buying it for $100 bucks, is it only reselling for $10? Does it immediately depreciate and lose 90% of its value?"
The startup's timing couldn't be better. As consumers increasingly seek both value and sustainability, Phia positions itself at the intersection of two major shopping trends. The platform's AI shopping advisor - currently in beta with select users - analyzes factors like deal quality, retained value, and even sizing predictions based on users' previous orders and returns.
What sets Phia apart isn't just the technology but the founders' unconventional growth strategy. Rather than burning cash on traditional user acquisition, they've built audience through content creation, an ambassador program, and even launched their own podcast. "The ability to acquire hundreds of thousands of downloads at a very low cost through the podcast and the various different distribution vehicles has been really important," Kianni revealed.
