FreeModel

Access 10 FreeModel models through Mastra's model router. Authentication is handled automatically using the FREEMODEL_API_KEY environment variable.

Learn more in the FreeModel documentation.

.env

FREEMODEL_API_KEY=your-api-key

src/mastra/agents/my-agent.ts

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

const agent = new Agent({
  id: "my-agent",
  name: "My Agent",
  instructions: "You are a helpful assistant",
  model: "freemodel/claude-fable-5"
});

// 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);
}

info

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

Models

10 available models

Model	Context	Tools	Reasoning	Image	Audio	Video	Input $/1M	Output $/1M
freemodel/claude-fable-5	1.0M						$10	$50
freemodel/claude-haiku-4-5-20251001	200K						$1	$5
freemodel/claude-opus-4-6	1.0M						$5	$25
freemodel/claude-opus-4-7	1.0M						$5	$25
freemodel/claude-opus-4-8	1.0M						$5	$25
freemodel/claude-sonnet-4-6	1.0M						$3	$15
freemodel/gpt-5.3-codex	400K						$2	$14
freemodel/gpt-5.4	1.1M						$3	$15
freemodel/gpt-5.4-mini	400K						$0.75	$5
freemodel/gpt-5.5	1.1M						$5	$30

Advanced configuration

Custom headers

src/mastra/agents/my-agent.ts

const agent = new Agent({
  id: "custom-agent",
  name: "custom-agent",
  model: {
    url: "https://cc.freemodel.dev/v1",
    id: "freemodel/claude-fable-5",
    apiKey: process.env.FREEMODEL_API_KEY,
    headers: {
      "X-Custom-Header": "value"
    }
  }
});

Dynamic model selection

src/mastra/agents/my-agent.ts

const agent = new Agent({
  id: "dynamic-agent",
  name: "Dynamic Agent",
  model: ({ requestContext }) => {
    const useAdvanced = requestContext.task === "complex";
    return useAdvanced
      ? "freemodel/gpt-5.5"
      : "freemodel/claude-fable-5";
  }
});

Direct provider installation

This provider can also be installed directly as a standalone package, which can be used instead of the Mastra model router string. View the package documentation for more details.

npm

npm install @ai-sdk/anthropic

pnpm

pnpm add @ai-sdk/anthropic

Yarn

yarn add @ai-sdk/anthropic

Bun

bun add @ai-sdk/anthropic