Founder (solo project) · 2025 – present · zone-prepa.com
The product
A physical notebook for students in French classes préparatoires. After each exercise, students write down the technique or theorem they were missing in one of 600 guided blocks, then review them before exams.
Sold at €29.99, printed on demand and shipped across France. Rated 4.9/5 on Trustpilot.
A fully automated business
I built the whole system alone, with Claude Code (an AI coding agent) as my development partner. Once a customer pays, no human step is needed:
- The customer pays on the website through Stripe.
- Stripe sends a secure notification (webhook) to my server.
- The server sends the confirmation emails and orders the printing through the Lulu Print API.
- Lulu prints the notebook and ships it to the customer.
- The purchase is reported to Meta (Pixel + Conversions API) to measure and optimize ads.
Under the hood
- Website: Next.js, deployed on Netlify. Every
git pushgoes live in about a minute. - No database: Stripe is the single source of truth, so the site can be redeployed without losing an order.
- Security: prices are recomputed on the server, card data never touches the site, and webhooks are cryptographically verified.
- No lost orders: Stripe retries failed notifications for 3 days, and a nightly job emails a backup CSV of all orders.
- Ads optimized on profit: each sale is reported to Meta with its real margin, not its price, so campaigns optimize for profit.
Results
340+ sales and €9,000 in revenue in the first year, with zero inventory and no upfront costs.