The latest articles on DEV Community by Houss (@houssjd). https://dev.to/houssjd https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F4216091%2F0b498523-37a7-4fa2-817d-c59eeff92951.png https://dev.to/houssjd en Houss Thu, 29 Oct 2026 21:38:43 +0000 https://dev.to/houssjd/building-a-shared-baby-with-nextjs-and-nestjs-4jdb https://dev.to/houssjd/building-a-shared-baby-with-nextjs-and-nestjs-4jdb <p>I built Grow The Baby, a small web experiment with one baby shared by everyone. Visitors can pay €1 to add or remove one day of his age. He moves through different life stages, and the story ends at 100 years. There are two contribution leaderboards and a shared name that visitors can buy the right to change.</p> <p>The interesting engineering problem was keeping a collective game consistent while payments and visitors arrive independently.</p> <p>I kept the application in two parts: a Next.js frontend and a NestJS API, with MySQL and TypeORM. One database record holds the baby's age, name and current naming price. The browser displays that state; it doesn't decide whether a paid action succeeded. The character uses SVG and CSS animations rather than a game engine.</p> <p>For payments, the API first stores a pending purchase and creates a Stripe Checkout session. Returning to the success URL does not change the game. The change happens only when the API receives a signed checkout completion event with a paid status. It also checks the session ID, amount, currency and payment mode against the stored purchase.</p> <p>Retries need their own handling. Checkout creation uses an idempotency key. The webhook locks the purchase record inside a database transaction and checks whether it has already been completed. Updating the game and recording completion happen together, so a repeated event doesn't add the same days twice. The shared game record is locked during updates too.</p> <p>After a committed change, the API sends the updated state through Server-Sent Events. This fits the current single-process deployment: visitors receive updates without polling, and there is no separate message broker.</p> <p>The site is live at <a href="https://growthebaby.com" rel="noopener noreferrer">https://growthebaby.com</a>.</p> <p>I'd appreciate feedback on one specific UX question: before opening the contribution form, is it clear that your action changes the same baby for every visitor?</p> showdev webdev