When Phia’s founders Phoebe Gates and Sophia Kianni decided to build an AI startup, they targeted an area they understood well: online shopping. The founders, who met at Stanford when they were randomly paired up as roommates, understood e-commerce because they had spent hours trying to find the right items to expand their wardrobe. They realized that AI had the potential to help people discover, shop, and buy in new ways. They also saw that this capability was a market opportunity.
Phoebe Gates explained the vision on stage at TechCrunch Disrupt 2025, stating there was a giant white space for helping people decide what they should actually buy. She questioned why everyone does not have a personal shopper in their pocket.
The startup began as a class project where it proved its initial demand. However, the service did not launch to the public until Phia found the right product-market fit, according to Kianni.
The tool is available as a browser extension and app. It lets shoppers compare prices, including for second-hand items, which adds a sustainability factor to the shopping experience. Phia says it integrates with more than 150 second-hand platforms and has over 350 million items in its in-house search database. Kianni pointed out that buying second-hand represents an 80 percent reduction in carbon footprint compared with buying new. She also noted that it is cheaper.
Kianni said the service also helps users understand the value of what they are buying. For example, if you are looking at a five hundred dollar handbag on Phia, you can quickly understand if you can resell that item for three or four hundred dollars. Conversely, if it is a fast-fashion piece you are buying for one hundred dollars, you can see if it only resells for ten dollars and immediately depreciates, losing ninety percent of its value.
The startup is also developing an AI shopping advisor. This advisor will help users understand value factors like a good deal or an item’s potential retained value. It will also address fashion basics, such as whether an item will fit based on the user’s previous orders and returns. The founders said the sizing insights feature is currently in beta with a small group of users.
The founders have used various tactics to attract an audience. These include an ambassador program, creating their own content about the product’s development, and even starting a podcast.
Kianni said the ability to acquire hundreds of thousands of downloads at a very low cost through the podcast and other distribution vehicles has been really important.
Gates added that sharing the realities of building a startup with their audience helped Phia’s potential users connect with the founders and their story. She said they had to go through a bit of an ego death. At first, they wanted to look good in all their content, but to make people engage with it and produce the necessary volume, they needed to pull back the curtain.
Gates, whose father is Bill Gates, acknowledges that she comes to the startup experience from a position of privilege. However, she says they do not necessarily go to him for advice. She explained that while she thinks her dad is a genius, he is not the one shopping on Phia. He is not hunting for the best deal across different sites or comparing his wish list items for a spring break trip.