Fumo is a Chrome add-on designed to help users make more informed financial decisions during online shopping. It detects when users are on an online checkout page and provides a reminder of the potential opportunity cost of spending money instead of investing it. Specifically, Fumo calculates how much the total purchase amount could have returned if it had been invested in the Vanguard Total Index (VTI) fund.

This tool serves as a practical approach to combat impulsive buying behaviors by prompting users to consider the long-term benefits of investing their money. By integrating seamlessly into the online shopping experience, Fumo aims to encourage users to think critically about their spending habits and prioritize their financial health.