Vercel AI SDK
TypeScript SDK for building AI-powered applications. Unified API across 20+ LLM providers (OpenAI, Anthropic, Google, Mistral, xAI, etc.) with a single import. Streaming-first with React/Next.js hooks (useChat, useCompletion). Supports tool calling, structured output (Zod schemas), and multi-step agents. Not an LLM provider — it's an orchestration layer that wraps provider SDKs. Free and open-source.
Overview
| Category | Ai |
| Ecosystem | vercel |
| Self-Hostable | Yes |
| On-Prem | No |
| Best For | hobby, startup, growth |
| Last Verified | 2026-02-12 |
Strengths & Weaknesses
Strengths:- dx
- performance
- TypeScript/JavaScript only — no Python SDK
- Adds abstraction layer that may hide provider-specific features
- Tightly coupled with Vercel/Next.js ecosystem
When to Use
Best when:- Building AI features in Next.js or React apps
- Want to switch between LLM providers without code changes
- Need streaming chat UI components
- TypeScript-first development
- Not using TypeScript/JavaScript
- Need deep provider-specific features
- Building Python-based ML pipelines
Known Issues (10)
- [critical] retry strategies and fallbacks
- [critical] Add support for OpenAI `realtime` voice models.
- [high] convert model messages to ui messages
- [medium] In useChat in @ai-sdk/react, state sent via `transport#body` is always stale
- [medium] claude sonnet 4 extended thinking requires thinking block on final message
- [medium] TypeError when using useChat onFinish with resume enabled
- [medium] resumable stream should get stopped when abort signal is sent
- [medium] Resume stream invalid state: controller is already closed
- [medium] event: errors in OpenAI reasoning stream result in finishReason=unknown
- [medium] Bug Report: `chat.stop()` abort signal not detected on backend with `createUIMessageStream`