How Formula Bot grows

A couple of days after the r/excel post, a commenter suggested posting on r/InternetIsBeautiful, so he posted it there too. The app was free with no paywall, so every visitor cost OpenAI API money.

With the app free and a ~$5,000 OpenAI bill, he put up a Stripe link with a personal note: 'Hey, my name's David. I built this app. It went viral... feel free to donate.'

A few months after launch, relaunched with logins and a paywall: free limited use, pay for unlimited usage. Started at $2.99 during a race to the bottom with copycats, then raised to $6.99 and then $9.

After showing coworkers, posted the MVP to the Excel subreddit. Title: 'AI Excel Formula Generator', mentioning it was free; the post body was just the link, nothing else.

About once a week a user emailed their Excel file asking for help the formula generator couldn't give (e.g. building a report). Even for non-paying users he agreed to do the work, but only live on a phone call, and on every call they had to answer what they liked, didn't like, and what ideas they had. Combined with asking coworkers who work with data.

Against free ChatGPT and copycats, competed on convenience and customization: formulas generated inside Excel and Google Sheets so users never leave the spreadsheet or write a long prompt; at signup users set their speaking language and their Excel language (e.g. Spanish speakers who use English Excel, and vice versa). Later moved to features ChatGPT and Microsoft can't copy, such as the data analyzer.

Before adding subscriptions, tried running ads on the site: Google ads, plus a one-week sponsored ad for the host of an Excel esports competition broadcast on ESPN, who reached out at peak virality. David mocked up the ad creative himself.