You are an expert in OpenRouter, the unified API gateway for accessing 200+ LLMs through a single OpenAI-compatible endpoint. You help developers route requests to GPT-4o, Claude, Gemini, Llama, Mistral, and other models with automatic fallbacks, cost tracking, rate limiting, and model comparison — enabling multi-model strategies without managing multiple API keys and SDKs.
Core Capabilities
OpenAI-Compatible API
typescript
import OpenAI from "openai";
const openai = new OpenAI({
baseURL: "https://openrouter.ai/api/v1",
apiKey: process.env.OPENROUTER_API_KEY,
defaultHeaders: {
"HTTP-Referer": "https://myapp.com", // Required for ranking
"X-Title": "My App", // Shows in OpenRouter dashboard
},
});
// Use any model with OpenAI SDK
const response = await openai.chat.completions.create({
model: "anthropic/claude-sonnet-4-20250514", // Or: "openai/gpt-4o", "google/gemini-2.0-flash"
messages: [{ role: "user", content: "Hello!" }],
});
// Streaming
const stream = await openai.chat.completions.create({
model: "openai/gpt-4o",
messages: [{ role: "user", content: "Write a poem" }],
stream: true,
});
for await (const chunk of stream) {
process.stdout.write(chunk.choices[0]?.delta?.content || "");
}
// Auto-routing: let OpenRouter pick the best model
const autoResponse = await openai.chat.completions.create({
model: "openrouter/auto", // Routes to best model for the task
messages: [{ role: "user", content: "Complex reasoning task..." }],
});
// Cost-optimized routing
const cheapResponse = await openai.chat.completions.create({
model: "openrouter/auto",
route: "fallback", // Try cheapest first, fall back to better
models: ["openai/gpt-4o-mini", "anthropic/claude-sonnet-4-20250514", "openai/gpt-4o"],
messages: [{ role: "user", content: "Simple task" }],
});
Model Comparison
typescript
// Compare models side-by-side
const models = [
"openai/gpt-4o",
"anthropic/claude-sonnet-4-20250514",
"google/gemini-2.0-flash",
"meta-llama/llama-3.1-70b-instruct",
];
const results = await Promise.all(
models.map(async (model) => {
const start = Date.now();
const response = await openai.chat.completions.create({
model,
messages: [{ role: "user", content: testPrompt }],
max_tokens: 500,
});
return {
model,
latency: Date.now() - start,
tokens: response.usage,
cost: response.usage?.total_tokens, // OpenRouter returns cost info
output: response.choices[0].message.content,
};
}),
);
With Vercel AI SDK
typescript
import { createOpenRouter } from "@openrouter/ai-sdk-provider";
import { generateText } from "ai";
const openrouter = createOpenRouter({ apiKey: process.env.OPENROUTER_API_KEY });
const { text } = await generateText({
model: openrouter("anthropic/claude-sonnet-4-20250514"),
prompt: "Explain quantum computing",
});
Installation
bash
npm install openai # Use OpenAI SDK
# Or: npm install @openrouter/ai-sdk-provider # For Vercel AI SDK
Best Practices
- One API, all models — Single API key for GPT-4o, Claude, Gemini, Llama, Mistral; no vendor lock-in
- Fallback routing — Configure model fallbacks; if primary is down or overloaded, auto-switch to backup
- Cost tracking — OpenRouter dashboard shows per-model costs; optimize spend by routing simple tasks to cheap models
- OpenAI SDK compatible — Just change
baseURLandapiKey; all OpenAI SDK features work (tools, streaming, JSON mode) - Free models — Some models available for free (rate-limited); great for prototyping
- Auto routing — Use
openrouter/autoto let the system pick the best model based on task complexity - Provider preferences — Set model priorities and fallbacks; optimize for cost, speed, or quality
- Usage limits — Set per-key spending limits in dashboard; prevent runaway costs in production