Mastra

What it does

Mastra is an open-source TypeScript framework for building AI agents and AI-powered applications. Developers define agents with models, tools, and instructions, and build workflows in TypeScript code. Running a project locally opens Mastra Studio at localhost:4111, where agents, workflows, and tools can be built and tested. Outputs include agent responses, workflow results, traces, and evaluation scores.

Developers use Mastra to define agents with models and tools, build multi-step workflows with branch and parallel control flow, add memory, and expose agents or tools as MCP servers. Observability traces agent calls and token usage, and built-in scorers evaluate outputs. Models are reached through a router that connects to many providers via one interface.

Mastra suits TypeScript developers building customer-facing assistants, internal copilots, or automation workflows. The core framework is Apache 2.0 licensed and free to use. Running it requires a Node.js environment and a model provider API key, such as OPENAI_API_KEY. Hosted Platform features are priced separately, and enterprise features are under a source-available license.

What it can do

• Define agents with models, tools, memory and instructions
• Build workflows with .then(), .branch() and .parallel() control flow
• Human-in-the-loop suspension and resumption of workflows
• Author MCP servers exposing agents and tools
• Built-in scorers, custom evals and observability tracing
• Input/output guardrails against prompt injection

Works with

• React
• Next.js
• Node
• Express
• SvelteKit
• Hono
• Astro
• Vite

Example workflows

Customer support agent with tools

Inputs: an agent definition with instructions and a tool created via createTool. Steps: register the agent in src/mastra/index.ts, then call agent.generate() after retrieving it by id. Output: a generated response from the agent using the chosen model.

Order fulfillment workflow with approval

Inputs: an order schema. Steps: chain validateInventory then createShipment with .then(), commit the workflow, and suspend for human approval if needed before resuming. Output: a completed multi-step process with stored execution state.

Before you choose

• Model ID examples differ across source pages; confirm current model names in the models directory before use.
• Model API usage is billed by the provider or gateway and is separate from any Mastra Platform subscription.
• Enterprise features require a separate source-available license and custom pricing.

Listed under

• Coding
• DevOps and observability
• Agent framework
• AI agents
• Developer tools
• Observability
• Open source
• Typescript

Get started

Requires a model provider API key set as an environment variable.

1. Run npm create mastra@latest <project-name> -- --llm <provider> to scaffold a project.
2. Set the provider API key environment variable, e.g. OPENAI_API_KEY.
3. Start the dev server with npm run dev and open Studio at http://localhost:4111.

Core framework is free and open source. Platform Starter is $0 with observability events, CPU time and retention limits, with overages. Teams is $250/month. Custom pricing for enterprise. Model API tokens are billed separately.

Source: mastra.ai/pricing, checked 29 Oct 2026. Prices can change; check before you buy.

Sources for this overview

Product pages, documentation, and pricing checked 29 Oct 2026. Each source supports part of the overview; availability and prices can change.

• TypeScript AI Framework for Agents and Apps | Mastra ↗mastra.ai
• Pricing | Mastra ↗mastra.ai
• Get started with Mastra | Mastra Docs ↗mastra.ai

Company website

mastra.ai: product, pricing and policy pages

YC directory mirror

Batch and company name

Social accounts

Accounts the company links, and its posts on X

Human review

Checked by a person

Last checked 29 Oct 2026. Every field keeps its source and date; unknown means we couldn’t confirm it.