OpenRouter

OpenRouter is a unified API gateway that gives you access to 500+ models from 60+ providers — OpenAI, Anthropic, Google, Meta, Mistral, and more — through a single endpoint and one API key.

Setup

1. Install packages

npm install @yourgpt/copilot-sdk @yourgpt/llm-sdk openai

3. Add environment variable

.env.local

OPENROUTER_API_KEY=sk-or-...

4. Streaming API route

app/api/chat/route.ts

import { streamText } from '@yourgpt/llm-sdk';
import { openrouter } from '@yourgpt/llm-sdk/openrouter';

export async function POST(req: Request) {
  const { messages } = await req.json();

  const result = await streamText({
    model: openrouter('anthropic/claude-3.5-sonnet'),
    system: 'You are a helpful assistant.',
    messages,
  });

  return result.toTextStreamResponse();
}

5. Generate text

import { generateText } from '@yourgpt/llm-sdk';
import { openrouter } from '@yourgpt/llm-sdk/openrouter';

const result = await generateText({
  model: openrouter('openai/gpt-4o'),
  prompt: 'Summarize the latest AI research.',
});

console.log(result.text);

Model IDs

OpenRouter model IDs follow the format provider/model-name:

// OpenAI
openrouter('openai/gpt-4o')
openrouter('openai/gpt-4o-mini')
openrouter('openai/o3-mini')

// Anthropic
openrouter('anthropic/claude-3.5-sonnet')
openrouter('anthropic/claude-3.5-haiku')
openrouter('anthropic/claude-3-opus')

// Google
openrouter('google/gemini-2.0-flash-001')
openrouter('google/gemini-2.0-pro-exp-02-05')

// Meta Llama
openrouter('meta-llama/llama-3.1-405b-instruct')
openrouter('meta-llama/llama-3.1-70b-instruct')

// Mistral
openrouter('mistralai/mistral-large')
openrouter('mistralai/mixtral-8x22b-instruct')

// DeepSeek
openrouter('deepseek/deepseek-chat')
openrouter('deepseek/deepseek-r1')

// Auto routing — OpenRouter picks the best model
openrouter('openrouter/auto')

Browse the full list at openrouter.ai/models.

Configuration

import { openrouter } from '@yourgpt/llm-sdk/openrouter';

// With site attribution (improves model availability)
const model = openrouter('anthropic/claude-3.5-sonnet', {
  apiKey: 'sk-or-...',
  siteUrl: 'https://myapp.com',
  appName: 'My App',
});

// Provider preferences — control which underlying providers are used
const model = openrouter('openai/gpt-4o', {
  providerPreferences: {
    allow: ['openai'],        // Only use OpenAI directly
    order: 'latency',         // 'price' | 'latency' | 'throughput'
  },
});

Fetch available models

import { fetchOpenRouterModels, searchOpenRouterModels } from '@yourgpt/llm-sdk/openrouter';

// Get all 500+ models
const models = await fetchOpenRouterModels();

// Search by name or provider
const claudeModels = await searchOpenRouterModels('claude');
const gptModels = await searchOpenRouterModels('gpt-4');

Tool Calling

OpenRouter passes tool calls through to the underlying model. Support varies by model — most frontier models handle it well:

import { generateText, tool } from '@yourgpt/llm-sdk';
import { openrouter } from '@yourgpt/llm-sdk/openrouter';
import { z } from 'zod';

const result = await generateText({
  model: openrouter('openai/gpt-4o'),
  prompt: 'What is the weather in Paris?',
  tools: {
    getWeather: tool({
      description: 'Get weather for a city',
      parameters: z.object({ city: z.string() }),
      execute: async ({ city }) => ({ temperature: 18, condition: 'cloudy' }),
    }),
  },
  maxSteps: 5,
});

With Copilot UI

app/providers.tsx

'use client';

import { CopilotProvider } from '@yourgpt/copilot-sdk/react';

export function Providers({ children }: { children: React.ReactNode }) {
  return (
    <CopilotProvider runtimeUrl="/api/chat">
      {children}
    </CopilotProvider>
  );
}

Next Steps

Fireworks - Fast open-source model inference
Fallback Chain - Automatic failover between providers
generateText() - Full LLM SDK reference

Configure reasoning through the modern openrouter() factory. Calls keep Chat Completions and the model's reasoning defaults unless you supply these options. See package availability before upgrading.

import { generateText, streamText } from "@yourgpt/llm-sdk";
import { openrouter } from "@yourgpt/llm-sdk/openrouter";

const model = openrouter("anthropic/claude-sonnet-4.5", {
  reasoning: { maxTokens: 1024 },
});
const result = await generateText({
  model,
  prompt: "Explain the result briefly.",
  maxTokens: 2048,
});
console.log(result.text);
console.log(result.reasoningText); // Optional provider-supplied summary/text

const stream = await streamText({
  model,
  prompt: "Continue.",
  maxTokens: 2048,
});
for await (const part of stream.fullStream) {
  if (part.type === "reasoning-delta") console.log(part.text);
}

Use reasoning.effort or reasoning.maxTokens, not both. Supported controls vary by model. enabled and exclude are also optional. Reasoning consumes the provider's output budget. The normal text stream remains answer-only.

For continuation, pass result.response.messages back as messages. The SDK keeps opaque providerMetadata.openrouter.reasoningDetails for replay; do not edit or reorder these blocks. Usage and the raw response are not part of that replay state. This option belongs to the modern openrouter() factory; it does not add reasoning controls to the legacy createOpenRouter() Runtime factory.