Fraudulent behavior on websites, such as account takeovers or mass creation of fake accounts, can be damaging to site owners and users. To combat this, browser fingerprinting is a useful method, identifying unique browser and device characteristics to detect fraud. The article focuses on preventing fraudulent mass signups by using Go to build a web app that captures browser fingerprints along with sign-up data. By integrating the Fingerprint Pro JS library, the app can recognize if a device attempts multiple quick sign-ups, rejecting new ones that happen too soon after a previous signup. The setup involves creating a Go project with a minimal web server, using SQLite for storage, and incorporating Fingerprint Pro for precise device identification. This approach enhances security without adding friction for legitimate users, offering a robust solution against fraudulent activities. Browser fingerprinting, unlike cookies, provides a persistent form of identification, effective even with stringent privacy settings.