Ecosystem and Maturity

How established, adopted, and actively developed each AI framework is.

Vercel AI SDK

Mature and widely adopted across the JS/TS ecosystem, closely associated with (but not dependent on) Vercel’s platform and the Next.js community.

TanStack AI

The newest framework in this category, released in alpha in early 2026 and reaching beta later that year — still young, but backed by the well-established TanStack ecosystem and team, and named AI Project of the Year at the 2026 Open Source Awards.

LangChain

One of the oldest and most widely adopted LLM frameworks, with the broadest integration catalog and largest community of any framework here, though sometimes criticized for API churn and abstraction overhead.

LangGraph

Newer than LangChain itself but has quickly become the recommended path for production, stateful agent workflows within the LangChain ecosystem, reaching a stable 1.0 release in 2026.

LlamaIndex

A mature, widely adopted project with a large community built specifically around RAG and data-connected LLM applications.

Mastra

A newer entrant, from the team behind Gatsby, that has grown quickly in the TypeScript agent space, often chosen over LangChain.js specifically for stronger type safety and faster local iteration.

CrewAI

A newer, fast-growing standalone project, popular for how quickly it gets a first multi-agent prototype running, reaching version 1.14 by 2026.

Semantic Kernel (Microsoft Agent Framework)

Backed directly by Microsoft; Semantic Kernel and AutoGen were merged into Microsoft Agent Framework 1.0 in April 2026, consolidating Microsoft’s agent tooling into a single, enterprise-backed framework.

Haystack

A mature project from deepset with a long track record specifically in production RAG and search/NLP pipelines, predating the current wave of general-purpose agent frameworks.