Lovable, formerly known as GPT Engineer, is an AI-powered full-stack application builder that reached $20M ARR within just 2 months of its rebrand, making it the fastest revenue ramp in European startup history. Users describe their application in natural language, and Lovable generates a complete React application with frontend UI, backend logic via Supabase, authentication systems, and payment processing through Stripe integration. The platform supports one-click deployment with built-in hosting, GitHub export for deploying to any platform, and custom domain configuration. Lovable features a Custom Knowledge system where users can provide project context such as branding guidelines or coding conventions that the AI remembers across edits. The Dev Mode provides direct code access for developers who want finer control. File upload capabilities support images and documents within generated applications. Lovable is designed for solo developers, freelancers, and small teams building production-ready web applications, internal tools, and rapid prototypes without extensive manual coding.