Mastra is a TypeScript-native agent framework built by a team with a background at Gatsby, aimed at the same gap the Vercel AI SDK addresses but with a broader scope specifically oriented toward building full agents rather than just AI-powered UI features. It bundles workflows, retrieval-augmented generation, persistent memory, and evaluation tooling into one framework rather than requiring a developer to assemble those pieces from separate libraries.
Its workflow engine lets developers define multi-step agent behavior with explicit control flow, similar in spirit to LangGraph but built JavaScript-first rather than ported over from a Python-first framework. That matters for teams whose whole stack, from the frontend to serverless functions, is already in TypeScript and would rather not introduce Python just for the agent layer.
Being open source and relatively new, it's building its following specifically among JavaScript and TypeScript teams who want a LangChain-equivalent that doesn't feel translated from Python, competing for that specific niche against the broader but Python-first incumbents.