LMStudio

Access 3 LMStudio models through Mastra's model router. Authentication is handled automatically using the LMSTUDIO_API_KEY environment variable.

Learn more in the LMStudio documentation.

LMSTUDIO_API_KEY=your-api-key

import { Agent } from "@mastra/core";

const agent = new Agent({
  name: "my-agent",
  instructions: "You are a helpful assistant",
  model: "lmstudio/openai/gpt-oss-20b",
});

// Generate a response
const response = await agent.generate("Hello!");

// Stream a response
const stream = await agent.stream("Tell me a story");
for await (const chunk of stream) {
  console.log(chunk);
}

OpenAI Compatibility

Mastra uses the OpenAI-compatible /chat/completions endpoint. Some provider-specific features may not be available. Check the LMStudio documentation for details.

Models

Model	Image	Audio	Video	Tools	Streaming	Context Window
lmstudio/openai/gpt-oss-20b	✗	✗	✗	✓	✗	131,072
lmstudio/qwen/qwen3-30b-a3b-2507	✗	✗	✗	✓	✗	262,144
lmstudio/qwen/qwen3-coder-30b	✗	✗	✗	✓	✗	262,144

Advanced Configuration

Custom Headers

const agent = new Agent({
  name: "custom-agent",
  model: {
    url: "http://127.0.0.1:1234/v1",
    modelId: "openai/gpt-oss-20b",
    apiKey: process.env.LMSTUDIO_API_KEY,
    headers: {
      "X-Custom-Header": "value",
    },
  },
});

Dynamic Model Selection

const agent = new Agent({
  name: "dynamic-agent",
  model: ({ runtimeContext }) => {
    const useAdvanced = runtimeContext.task === "complex";
    return useAdvanced
      ? "lmstudio/qwen/qwen3-coder-30b"
      : "lmstudio/openai/gpt-oss-20b";
  },
});