The Vercel AI SDK is an open-source TypeScript toolkit for building AI-powered applications and streaming UIs with frameworks like Next.js, React, Svelte, and Vue. It provides unified interfaces for working with multiple AI providers including OpenAI, Anthropic, and Google, with built-in streaming, tool calling, and structured output support. Frontend and full-stack developers building AI features in web applications use the Vercel AI SDK to implement AI capabilities with significantly less boilerplate, consistent patterns across providers, and first-class support for streaming responses that create responsive, modern AI user experiences.