OpenRouter Has a Free API — Access 200+ AI Models Through One Endpoint

#ai #openrouter #api #llm

TL;DR

OpenRouter provides a unified API to access 200+ AI models — GPT-4, Claude, Gemini, Llama, Mistral, and more — through one OpenAI-compatible endpoint. Some models are free, and you can switch providers without changing code.

What Is OpenRouter?

OpenRouter is an AI model router:

200+ models — GPT-4o, Claude 3.5, Gemini, Llama 3, Mistral, etc.
One API — OpenAI-compatible format
Free models — several open-source models available for free
Automatic fallbacks — if one provider is down, routes to another
Usage tracking — monitor spend across all models
Pay-per-use — no subscriptions, pay only for what you use

Quick Start

npm install openai  # OpenRouter uses OpenAI-compatible API

import OpenAI from "openai";

const openrouter = new OpenAI({
  baseURL: "https://openrouter.ai/api/v1",
  apiKey: "sk-or-YOUR_KEY",
});

const completion = await openrouter.chat.completions.create({
  model: "anthropic/claude-sonnet-4-20250514",
  messages: [
    { role: "user", content: "Explain quantum computing in 3 sentences" },
  ],
});

console.log(completion.choices[0].message.content);

Switch Models Without Changing Code

// Just change the model string!
const models = [
  "openai/gpt-4o",
  "anthropic/claude-sonnet-4-20250514",
  "google/gemini-pro-1.5",
  "meta-llama/llama-3.1-405b-instruct",
  "mistralai/mistral-large",
];

async function askAI(model: string, prompt: string) {
  const response = await openrouter.chat.completions.create({
    model,
    messages: [{ role: "user", content: prompt }],
  });
  return response.choices[0].message.content;
}

// Compare outputs from different models
for (const model of models) {
  console.log(`\n--- ${model} ---`);
  console.log(await askAI(model, "Write a haiku about coding"));
}

Free Models

// These models are FREE on OpenRouter:
const freeModels = [
  "meta-llama/llama-3.2-3b-instruct:free",
  "mistralai/mistral-7b-instruct:free",
  "google/gemma-2-9b-it:free",
  "huggingfaceh4/zephyr-7b-beta:free",
];

// Use free models for testing, prototyping, or simple tasks
const response = await openrouter.chat.completions.create({
  model: "meta-llama/llama-3.2-3b-instruct:free",
  messages: [{ role: "user", content: "Hello!" }],
});

Streaming

const stream = await openrouter.chat.completions.create({
  model: "anthropic/claude-sonnet-4-20250514",
  messages: [{ role: "user", content: "Write a short story" }],
  stream: true,
});

for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta?.content || "");
}

Function Calling

const response = await openrouter.chat.completions.create({
  model: "openai/gpt-4o",
  messages: [{ role: "user", content: "What's the weather in Tokyo?" }],
  tools: [
    {
      type: "function",
      function: {
        name: "get_weather",
        description: "Get current weather for a location",
        parameters: {
          type: "object",
          properties: {
            location: { type: "string" },
          },
          required: ["location"],
        },
      },
    },
  ],
});

Python

from openai import OpenAI

client = OpenAI(
    base_url="https://openrouter.ai/api/v1",
    api_key="sk-or-YOUR_KEY",
)

response = client.chat.completions.create(
    model="anthropic/claude-sonnet-4-20250514",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(response.choices[0].message.content)

OpenRouter vs Direct APIs

Feature	OpenRouter	OpenAI Direct	Anthropic Direct
Models	200+	OpenAI only	Claude only
One API	Yes	Own format	Own format
Free models	Yes	No	No
Fallbacks	Automatic	Manual	Manual
Usage dashboard	All models	OpenAI only	Anthropic only
Pricing	Pass-through + small fee	Direct	Direct

Resources

Building AI apps with web data? My Apify scraping tools extract data from any website — feed it to any AI model through OpenRouter. Questions? Email spinov001@gmail.com

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