Hello and welcome back to another exciting tutorial of GreatStack. In this video, instead of just using an AI tool, I show you how to build your own AI tool from scratch. We build and deploy a full stack AI Thumbnail Generator using the MERN stack (MongoDB, Express, React, Node.js) and the Google Gemini API. The app lets users sign up/login, enter a title, prompt, aspect ratio, color scheme, and style, then generate a thumbnail with one click. You also get download, delete, and a YouTube layout preview so you can instantly see how your thumbnail will look. I start by setting up the frontend using a pre-built animated React template, then I replace all the content (navbar, hero, features, testimonials, pricing, contact, CTA, footer) to match our thumbnail generator product. After that, we create the backend server, connect MongoDB, build authentication APIs, and create the thumbnail generation APIs powered by Gemini. Finally, we connect frontend to backend and deploy the project online for free, so you can add the live link to your resume or even submit it as a college project.