David's first users came from his full-time job colleagues, who were immediately impressed by the tool (they thought it took months to build; it took just two weeks using Bubble.io no-code). He then posted to the Excel subreddit (r/excel) with a simple post titled "AI Excel Formula Generator," mentioning it was free, and just dropped the link. Within minutes it was the top post of the day, then top post of the week, blowing up within the Excel community. A commenter then suggested he cross-post to r/InternetIsBeautiful. He did, and that post received around 10,000 upvotes and thousands of comments, driving thousands and thousands of visitors to the site in a matter of days. This single Reddit moment was the primary engine for his initial massive user spike.
Formula Bot (formerly XL Formula Bot)
AI-powered Excel and Google Sheets assistant for formulas, analysis, and data insights
9 moves, in order
- Pre launch / MVPWord of mouth colleagues
Showed the MVP to colleagues at his full-time job. They were amazed it was built in just two weeks and validated that it solved a real pain point (helping people with Excel formulas).
First handful of users; strong early validation - LaunchReddit organic post
Posted to r/excel with a simple title ('AI Excel Formula Generator') mentioning the tool was free and including only a link. No elaborate pitch.
Top post of the day, then top post of the week within the Excel subreddit - Viral spikeReddit organic post
Cross-posted to r/InternetIsBeautiful after a commenter suggested it. The post received ~10,000 upvotes and thousands of comments, driving viral traffic for months.
Thousands of users in days; went viral for months - Post viral crisisDonation link
After burning through ~$5,000 in OpenAI API costs in days, David put up a Stripe donation link explaining he was the solo builder and asking for optional contributions to keep the app alive.
Recouped a few thousand dollars; kept the product alive - Early monetizationSponsorship ad deal
Ran a paid ad for the ESPN-affiliated extreme sports Excel competition ('esports for Excel'). The host reached out directly at peak virality; David designed the creative himself and ran it for ~1 week.
Drove a ton of clicks; modest revenue but motivated him to keep going - Month 3 4Paywall subscription launch
Launched a proper paywall with logins and subscription tiers a few months after going viral, converting the free user base into paying customers.
First recurring revenue; ~5,000 paying users eventually - Product market fit expansionCustomer development calls
When users emailed Excel questions the tool couldn't answer and sent their actual files, David turned each request into a free 1-on-1 phone call — he'd do their work for them in exchange for product feedback and feature ideas. This directly shaped the roadmap beyond formula generation.
Roadmap evolved into a full data analytics platform; reduced churn drivers - Partnership / distributionMicrosoft addin store
Microsoft's add-ons team reached out and offered to build a Formula Bot add-in for the Excel add-on store for free. David accepted, gaining distribution inside Excel itself.
Listed in Microsoft's Excel add-on store; significant brand credibility boost - Scaling / moat buildingProduct expansion
Expanded from a single formula generator to three products: AI chat inside Excel/Google Sheets, formula generators, and a data analyzer (upload data → natural language queries → charts/analysis). Goal was to build features that ChatGPT and Microsoft couldn't replicate.
$26,000 MRR, 750,000 total users, 5,000 paying subscribersMRR $26k Users 750k users
Deep domain knowledge of Excel from a senior professional role, which gave him authentic insight into user pain points. He also had paternity leave (~6 weeks) providing a concentrated window to build and launch without distractions, and happened to launch at the very early wave of OpenAI API availability before competitors existed.
reddit_organic_post
Running Google Ads ("made a few bucks here and there, it just definitely wasn't worth the hassle"). Early pricing at $3/month was unsustainable and triggered a race-to-the-bottom with copycat competitors. Conversations with VCs went nowhere because he lacked a broader product vision beyond "more generators."
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