- What it is
- An open-source TypeScript library for AI apps and agents, under the Apache-2.0 licence. Version 7 shipped on 25 June 2026.
- Where it runs
- React, Next.js, Vue, Svelte, Node.js and more. Version 7 needs Node.js 22 or later and ESM imports; CommonJS require() is not supported.
- Three parts
- Core for text, structured objects, tool calls and agents. UI for chat hooks. Harnesses for running coding agents such as Claude Code and Codex.
- Changing models
- Vercel’s page says you switch providers with one line of code, with streaming and built-in fallbacks. It works with AI Gateway.
- New in version 7
- Tool approvals, durable WorkflowAgent runs, sandbox support and OpenTelemetry. Realtime voice and video generation are marked experimental.
- What it costs
- The library is free and open source. You pay for the models you call, through the provider or AI Gateway.