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Installation

npm install @ai-billing/openrouter @ai-billing/core @openrouter/ai-sdk-provider ai

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Overview

The @ai-billing/openrouter package provides middleware for tracking token usage and calculating costs when using OpenRouter models with the Vercel AI SDK.

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Usage

To use the middleware, wrap your OpenRouter model using wrapLanguageModel from the ai package and pass the createOpenRouterV3Middleware.
1

Initialize the OpenRouter provider

First, set up the OpenRouter provider using your API key.
import { createOpenRouter } from '@openrouter/ai-sdk-provider';

const openrouter = createOpenRouter({
  apiKey: process.env.OPENROUTER_API_KEY,
});
2

Create the billing middleware

Initialize the OpenRouter billing middleware. You need to provide a destination (such as consoleDestination) where billing events will be sent.
import { createOpenRouterV3Middleware } from '@ai-billing/openrouter';
import { consoleDestination } from '@ai-billing/core';

const billingMiddleware = createOpenRouterV3Middleware({
  destinations: [consoleDestination()],
});
3

Wrap the model

Use wrapLanguageModel from the ai package to apply the billing middleware to your OpenRouter model.
import { wrapLanguageModel } from 'ai';

const wrappedModel = wrapLanguageModel({
  model: openrouter('google/gemini-2.0-flash-001'),
  middleware: billingMiddleware,
});
4

Use the wrapped model

Finally, use the wrapped model with AI SDK functions like generateText or streamText. The billing middleware will automatically track tokens and handle metrics.
import { generateText } from 'ai';

const result = await generateText({
  model: wrappedModel,
  prompt: 'What is the capital of Sweden?',
});