API reference

Anthropic Messages

Use Anthropic's SDK and /v1/messages format with every chat model.

POST https://api.routerplex.com/v1/messages

RouterPlex accepts Anthropic's Messages API request format and returns Anthropic-format responses for every chat model in the catalog — Claude, GPT, Gemini, DeepSeek, Kimi, Qwen, and more. The same RouterPlex key and prepaid balance work across both API formats.

Anthropic SDK base URL: https://api.routerplex.com — do not append /v1; the SDK adds /v1/messages itself.

curl #

bash

curl https://api.routerplex.com/v1/messages \
  -H "x-api-key: $ROUTERPLEX_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{
    "model": "gpt-5.4",
    "max_tokens": 256,
    "messages": [{"role": "user", "content": "Explain HTTP in one line"}]
  }'

Authorization: Bearer $ROUTERPLEX_KEY also works if your HTTP client already uses bearer authentication.

Python SDK #

python

import os
from anthropic import Anthropic
 
client = Anthropic(
    base_url="https://api.routerplex.com",
    api_key=os.environ["ROUTERPLEX_API_KEY"],
)
 
message = client.messages.create(
    model="gemini-3.5-flash",
    max_tokens=256,
    messages=[{"role": "user", "content": "Explain HTTP in one line"}],
)
print(message.content[0].text)

TypeScript SDK #

typescript

import Anthropic from "@anthropic-ai/sdk";
 
const client = new Anthropic({
  baseURL: "https://api.routerplex.com",
  apiKey: process.env.ROUTERPLEX_API_KEY,
});
 
const message = await client.messages.create({
  model: "deepseek-v4-pro",
  max_tokens: 256,
  messages: [{ role: "user", content: "Explain HTTP in one line" }],
});
console.log(message.content);

Streaming #

Set stream: true or use the Anthropic SDK's streaming helper. RouterPlex returns Anthropic SSE events such as message_start, content_block_delta, and message_stop, including when the selected model is not a Claude model.

Which format should I use? #

Client	Base URL	Format
OpenAI SDKs and OpenAI-compatible tools	`https://api.routerplex.com/v1`	`/v1/chat/completions`
Anthropic SDK and Claude Code	`https://api.routerplex.com`	`/v1/messages`

Both formats reach the same 36 chat models and deduct from the same balance. gpt-image-2 is image-generation only and uses /v1/images/generations, not a chat endpoint. Tool use, vision, thinking, and structured-output support still depend on the selected model.