I built an AI Excel tool that never uploads your files. Here's how.

I just launched FormulaAI — an AI-powered Excel tool that prioritizes privacy. Most AI Excel tools, however, upload your entire file to their servers. This means sensitive data such as financial information or customer lists could be stored on someone else's server. I wanted to create a different experience. FormulaAI offers two core features:

First, you can Upload Excel and describe changes in plain English. The AI then modifies the table, and you can see every alteration in a diff view. Once you confirm, you can download the updated file.

Second, you can Generate Tables without needing a file. Simply describe what you want, such as generating a March sales budget with categories, budget amounts, actual spend, and variance. The AI creates a complete spreadsheet for you.

The privacy architecture ensures that files are parsed locally in the browser using SheetJS. Only data summaries are sent to the AI for processing. No files are stored on the server, and everything is deleted after processing.

Technologies used include Next.js + TypeScript, DeepSeek API, SheetJS, Supabase, and Cloudflare Pages. A free tier offers a monthly quota, while a paid plan provides unlimited usage. Early supporters who signed up before the launch receive a permanent discount.

You can try it at https://formulaai.net. I welcome your feedback!