Mastra

Mastra is a TypeScript-first, open-source framework for building AI agents and applications, created by the team behind Gatsby. Licensed under Apache 2.0 for its core, it lets developers go from early prototypes to production-ready agents using a modern JavaScript stack. The project has accumulated over 24,000 GitHub stars and reached its latest release, @mastra/core@1.35.0, in May 2026.

What It Is

Mastra is an agentic framework that provides the primitives TypeScript developers need to build, test, and deploy AI-powered products. It covers the full lifecycle: defining agents with LLMs and tools, orchestrating multi-step workflows, managing memory and context, connecting to external services via MCP, evaluating output quality, and observing production behavior. The framework integrates with popular web frameworks like Next.js, Express, Hono, and SvelteKit, or can be deployed as a standalone server.

Core Capabilities

Mastra bundles several distinct building blocks into one cohesive package:

• Model routing — connects to 40+ providers (OpenAI, Anthropic, Gemini, and more) through a single standard interface, with access to 3,000+ models via the Mastra model router.
• Agents — autonomous LLM-driven agents that reason about goals, select tools, and iterate until a stopping condition is met.
• Workflows — a graph-based workflow engine with an intuitive control-flow syntax (.then(), .branch(), .parallel()) for deterministic multi-step processes.
• Human-in-the-loop — suspend and resume agents or workflows awaiting user input, with execution state persisted in storage.
• Memory — conversation history, working memory, and semantic recall so agents behave coherently across sessions.
• MCP servers — author and expose Model Context Protocol servers, making agents and tools accessible to any MCP-compatible system.
• Evals and observability — model-graded, rule-based, and statistical evaluation methods, plus built-in tracing and logging integrated with external observability platforms.

Deployment Model

Mastra agents can be embedded inside existing React, Next.js, or Node.js applications, or deployed as standalone API endpoints via the Mastra Server. The platform layer (Mastra Studio, observability dashboard, and Memory Gateway) is available as a hosted cloud service or as a self-hosted option. The core framework is fully open source under Apache 2.0; enterprise features in ee/ directories are source-available under a separate Mastra Enterprise License and require a valid license for production use.

Who Builds With It

According to the Mastra website, the framework is used by teams at Replit, Sanity, SoftBank, WorkOS, Factorial, and Elastic, among others. Documented use cases span customer-facing assistants, internal copilots, data analysis agents, content automation, DevOps automation, and sales workflow tooling.

Update: @mastra/core v1.35.0 (May 2026)

The latest published release is @mastra/core@1.35.0, released on May 15, 2026. The GitHub repository shows active development with a last push on May 20, 2026, 389 open issues, and over 2,000 forks. The about page notes the team has grown to more than 35 people and has raised a $13M seed round from Gradient, Basecase, and Y Combinator. The project describes itself as getting millions of downloads per month, per vendor-published claims on the about page.

Setup Path

Getting started requires a single command — npm create mastra@latest — which scaffolds a new project and opens Mastra Studio, a local interactive UI for building, testing, and managing agents and workflows. The framework supports npm, pnpm, Yarn, and Bun. Integration guides exist for Next.js, React (Vite), Astro, Express, SvelteKit, and Hono.