Many users need to perform spreadsheet-like calculations but don't want to open separate apps or deal with clunky web interfaces. A Chrome extension could bring this functionality directly into the browser, enabling quick calculations without disrupting workflow.
You'd build a lightweight extension that lets users perform common spreadsheet functions (sums, averages, etc.) directly on web pages or in a sidebar. It should integrate with existing data sources and allow easy data manipulation.
Freelancers, analysts, and small business owners would pay for premium features like advanced formulas or data visualization tools.
The smallest first version could focus on basic arithmetic operations and a simple UI for inputting data.
The biggest risk is competition from existing spreadsheet apps that users might prefer for complex tasks.