Quick Start

Introduction

LMRouter is an open-source, all-in-one API router that gives AI developers a single, unified way to connect to the best model providers. It provides OpenAI and Anthropic compatible API endpoints, so you can use it with any OpenAI or Anthropic compatible client.

Using the OpenAI-Compatible Endpoint

You are able to drop-in replace your OpenAI endpoint with the LMRouter endpoint, and use the LMRouter API key:

import OpenAI from "openai";

const main = async () => {
  const openai = new OpenAI({
    baseURL: "https://api.lmrouter.com/openai/v1",
    apiKey: "<LMROUTER_API_KEY>",
    defaultHeaders: {
      "HTTP-Referer": "<YOUR_SITE_URL>",
      "X-Title": "<YOUR_SITE_NAME>",
    },
  });

  const completion = await openai.chat.completions.create({
    model: "openai/gpt-4o",
    messages: [
      {
        role: "user",
        content:
          'How many times does the letter "R" appear in the word "LMRouter"?',
      },
    ],
  });

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

main();

Apart from the chat completions endpoint, LMRouter also supports

• Image generation
• Image editing
• Embeddings
• Responses
• Audio speech
• Audio transcriptions
• Audio translations

endpoints.

Using Claude Code

You are able to use the LMRouter Anthropic-compatible endpoint with Claude Code by setting the ANTHROPIC_BASE_URL and ANTHROPIC_AUTH_TOKEN environment variables. You are able to use any model provided by LMRouter with Claude Code:

ANTHROPIC_BASE_URL=https://api.lmrouter.com/anthropic \
ANTHROPIC_AUTH_TOKEN=$LMROUTER_API_KEY \
ANTHROPIC_MODEL=$MODEL_NAME claude