CartAI is a developer-first AI agent platform that automates web-based transactions through a single API. It navigates any web property to complete checkouts, subscription sign-ups, invoice payments, and order submissions. The platform includes a PCI-compliant payment stack, composable workflow primitives, and cooperative bot-mitigation via signed agent identity. CartAI also offers an MCP server for AI agent integration and a drop-in hosted cart component, all built on the same underlying transaction primitive.