Mastra: TypeScript AI Agent Framework
Mastra is a modern TypeScript framework for building AI agents. The pitch from the team is sharp: "Python trains, TypeScript ships." If most of your production stack runs on Node.js, Next.js, or Bun, running your agent in TypeScript removes a language boundary you would have hit with LangChain or LlamaIndex. As of May 2026, the GitHub repo has 24.1k+ stars under an Apache 2.0 license.
The 30-second version
- What: open-source TypeScript framework for AI agents
- Who: TypeScript developers shipping production AI features
- Price: free (Apache 2.0)
- Best at: agents inside a TypeScript backend or full-stack app
- Verdict: pick Mastra when TypeScript is your default; pick LangChain when Python is
What Mastra actually is
Mastra is the TypeScript-first answer to LangChain. The framework is designed from scratch in TypeScript, which means type safety end-to-end and a build experience that fits an existing Node.js or Next.js project. You install it from npm, define agents and tools in TypeScript, and deploy alongside the rest of your backend.
The team's framing is that Python is the right language for research and training, while TypeScript is the right language for production deployment. Most B2B SaaS and consumer web apps in 2026 are TypeScript on the backend. Putting your agent code in the same runtime as your API removes context-switching overhead and lets you share types between the agent and the rest of the app.
The GitHub repo activity in 2026 (24.1k stars at last check) suggests genuine momentum. Mastra is one of the few serious TypeScript-native agent frameworks in the category, alongside the Vercel AI SDK and LangChain JS.
Key capabilities
- TypeScript-native agent and workflow primitives
- Type-safe tool definitions (the IDE knows what every tool returns)
- Memory and RAG primitives
- Provider-agnostic LLM support (OpenAI, Anthropic, Google, others)
- Built-in observability dashboards
- Workflows for orchestrating longer agent runs
- Apache 2.0 license
Pricing
Mastra is free under the Apache 2.0 license. You pay for LLM API spend and any infrastructure you deploy on. No first-party paid product as of May 2026.
Who Mastra fits
- TypeScript developers shipping AI features inside a Node.js or Next.js backend
- Teams that share types between frontend and backend (full-stack TypeScript)
- Anyone deploying to Vercel, Cloudflare Workers, or other JS-native runtimes
- Solo founders who want one language across their stack
Who Mastra does not fit
- Python-first teams (use LangChain, LlamaIndex, or PydanticAI)
- Data scientists and ML researchers (Python ecosystem is still richer)
- Anyone needing the absolute widest community and tutorial library
Mastra vs LangChain JS and Vercel AI SDK
| Axis | Mastra | LangChain JS | Vercel AI SDK |
|---|---|---|---|
| Language | TypeScript-native | TypeScript (Python port) | TypeScript-native |
| Type safety | Core value | Uneven | Strong |
| Agent maturity | Strong | Mature | Growing |
| Observability | Built-in dashboards | LangSmith | Vercel tools |
| Best for | TypeScript-first stacks | LangChain parity in TS | Next.js + Vercel deploys |
Pros and cons
Pros:
- True TypeScript-first design, not a Python port
- Type safety end-to-end, easier for IDEs to assist
- Apache 2.0 license is permissive enough for commercial use
- Built-in observability without paying for a separate SaaS
Cons:
- Smaller community than LangChain
- Fewer third-party tutorials
- Ecosystem of pre-built tools is younger than Python alternatives
How I'd use Mastra on SellerShorts
SellerShorts is a Next.js + TypeScript codebase. When I add an AI agent to our backend, I do not want to spin up a separate Python service if I can avoid it. Mastra lets me write the agent in the same repo, share types, and deploy together. I tested it for an internal seller-onboarding agent that helps tool builders define their AI Tool listings. The build experience felt clean. For a TypeScript shop, Mastra is the natural pick.
Try Mastra
Get started with Mastra
Install from npm. Open source under Apache 2.0. Best evaluated by running it inside an existing TypeScript backend.
Building Amazon-specific agents? See the Amazon AI hub.
Frequently asked questions
What is Mastra?
Mastra is a modern TypeScript framework for building AI-powered applications and agents. The team's positioning is 'Python trains, TypeScript ships,' meaning TypeScript is better suited for production deployment. As of May 2026 the GitHub repo has 24.1k+ stars.
Why TypeScript instead of Python?
Most production web apps in 2026 are TypeScript or JavaScript. If your team already ships a TypeScript backend (Next.js, NestJS, Hono), running your AI agent in the same runtime removes a whole language barrier. Mastra fits the TypeScript-first stack natively.
Mastra vs LangChain JS: which should I pick?
Mastra is TypeScript-native by design. LangChain JS is a port of the Python framework, which means the API can lag and the type safety is uneven. Pick Mastra when TypeScript is your primary language. Pick LangChain JS when you want feature parity with the larger Python LangChain ecosystem.
Is Mastra free?
Yes. Mastra is open source under the Apache 2.0 license. You pay for LLM API calls but not for the framework itself.