One API Key, Every Frontier Model: Call GPT-4o, Claude, and DeepSeek from One Endpoint

If you build with LLMs, you probably juggle multiple SDKs, API keys, and bills — one for OpenAI, one for Anthropic, one for Google. And every time you want to A/B-test a different model, you rewrite integration code.

There's a simpler pattern: one OpenAI-compatible endpoint that proxies every frontier model. You keep the official openai SDK, change the base_url, and switch models by changing the model parameter.

The idea

Vynex API exposes a single /v1 endpoint that speaks the OpenAI Chat Completions contract. Behind it: GPT, Claude, Gemini, DeepSeek, Qwen, and GLM. One key, one bill.

Python (drop-in migration)

from openai import OpenAI

# Only change: base_url
client = OpenAI(
    api_key="vynex-xxx",
    base_url="https://llm-api.vynexcloud.com/v1"
)

# Call GPT-4o
r = client.chat.completions.create(
    model="gpt-4o",
    messages=[{"role": "user", "content": "Hello!"}]
)

# Switch to Claude — same code, just change model name
r = client.chat.completions.create(
    model="claude-3-5-sonnet",
    messages=[{"role": "user", "content": "Hello!"}]
)

# Switch to DeepSeek (5-10x cheaper, strong on reasoning)
r = client.chat.completions.create(
    model="deepseek-chat",
    messages=[{"role": "user", "content": "Hello!"}]
)

No new SDK. No rewrite. Just base_url + model name.

Node.js

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.VYNEX_API_KEY,
  baseURL: "https://llm-api.vynexcloud.com/v1",
});

const res = await client.chat.completions.create({
  model: "gpt-4o",
  messages: [{ role: "user", content: "Hello!" }],
});

cURL (no SDK needed)

curl https://llm-api.vynexcloud.com/v1/chat/completions \
  -H "Authorization: Bearer $VYNEX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Why this matters

Cost: Models like DeepSeek-V3 and Qwen cost 5-10x less than GPT-4o while performing well on most tasks. Use expensive models only where needed.
Chinese models for export: DeepSeek, Qwen, and GLM are available globally through Vynex — including regions where direct access is restricted (Russia, Iran, CIS).
USDT payment: No credit card required, USDT accepted — useful for global developers.
34+ models: GPT-4o, Claude 3.5, Gemini, DeepSeek, Qwen, GLM — all from one endpoint.