Alternatives

OpenAI Assistants API alternatives in 2026 (Anthropic MCP, Vercel AI SDK, LangGraph, Mastra, Inngest Agents)

Top OpenAI Assistants API alternatives in 2026: Anthropic MCP (open protocol), Vercel AI SDK (multi-model SDK), LangGraph (graph workflows), Mastra (TypeScript-native), Inngest Agents (durable execution).

Why people search this

People look for OpenAI Assistants alternatives because they want multi-model portability (Anthropic MCP, Vercel AI SDK), graph-shaped workflows (LangGraph), TypeScript-native ergonomics (Mastra), or durable execution (Inngest).

The ranking

#1

Anthropic MCP

Best for: Cross-vendor portability, IDE / dev tool integrations  ·  Price: Free protocol + per-token model cost

Open protocol for agent tools — works across Claude, GPT, Gemini, local models, IDE integrations.

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#2

Vercel AI SDK

Best for: Next.js / TypeScript apps, multi-model  ·  Price: Free SDK + per-token model cost

TypeScript-native multi-model SDK with streaming, tool calls, structured output across Claude, GPT, Gemini, more.

#3

LangGraph

Best for: Complex multi-step workflows, stateful agents  ·  Price: Free OSS + paid platform

Graph-based agent workflow engine from LangChain — stateful, checkpointed, observable agents.

#4

Mastra

Best for: TypeScript agent stacks, full-stack workflows  ·  Price: Free OSS

TypeScript-first agent framework with workflows, RAG, evals, observability built in.

#5

Inngest Agents

Best for: Production-reliable long-running agents  ·  Price: Free + paid

Durable agent execution on top of Inngest workflow engine — retries, state, observability for free.

FAQ

Free OpenAI Assistants alternative?

MCP protocol is free; Vercel AI SDK, LangGraph, Mastra are all free open-source.

Most portable alternative?

Anthropic MCP — open protocol, works with Claude/GPT/Gemini/local models.

Best for TypeScript?

Vercel AI SDK or Mastra — both TypeScript-native.

Related

Last updated: 2026-06-01.