The Flatmarket platform is a free, open-source static eCommerce solution that offers speed, security, and reliability. It features responsive design, the benefits of static sites, and the security of Stripe for payment processing. By using Flatmarket with Netlify, developers can create fast, secure, and scalable online stores without relying on heavy backend databases. The platform allows for easy deployment to GitHub and integration with Stripe and Heroku, making it a viable alternative for eCommerce businesses looking to improve their website's performance and security.