OpenAI-Compatible API: One base_url for Claude, GPT and Gemini

TL;DR#

"OpenAI-compatible" means an API speaks the same request/response format as OpenAI's Chat Completions endpoint. ClaudeN AI exposes one at https://clauden.ai/v1, plus an Anthropic-compatible route at https://clauden.ai/v1/anthropic. Keep the SDK you already use, change one base_url, and a single API key calls Claude, GPT and Gemini — switching models is just a string change. Signup includes a $5 free trial credit, and top-ups work with USDT or PayPal.

What "OpenAI-compatible" actually means#

The OpenAI Chat Completions format has become the de-facto lingua franca of LLM APIs: a POST /v1/chat/completions request with a model name and a messages array, answered in a well-known response shape, with optional streaming. Most SDKs, frameworks and tools — agent frameworks, IDE plugins, no-code builders — already speak it.

An OpenAI-compatible gateway accepts requests in exactly that shape and returns responses your client already understands. The practical consequence: anything that lets you configure an API key and a base URL can use it, with zero code changes.

Change one line, keep everything else#

from openai import OpenAI

client = OpenAI(
api_key="YOUR_CLAUDEN_KEY",
base_url="https://clauden.ai/v1", # the only line that changes
)

resp = client.chat.completions.create(
model="claude-sonnet-4-6",
messages=[{"role": "user", "content": "Summarize this repo's README."}],
)
print(resp.choices[0].message.content)
```

No new SDK to learn, no request-mapping code to maintain. The same works from cURL, JavaScript, Go — anything that can send the OpenAI format.

Switching models is a string change#

Because routing happens on the model field, comparing models becomes trivial:

• Set model to a Claude model (e.g. claude-sonnet-4-6) for Anthropic's models.
• Set it to a GPT model name for OpenAI's models.
• Set it to a Gemini model name for Google's models.

Run the same prompt across all three and compare the answers — no new accounts, no extra SDKs, no separate billing setups. The current model list is available in your ClaudeN dashboard.

Prefer the Anthropic SDK? Also covered#

ClaudeN is compatible with the Anthropic Messages format too, so the official anthropic SDK works the same way:

import anthropic

client = anthropic.Anthropic(
api_key="YOUR_CLAUDEN_KEY",
base_url="https://clauden.ai/v1/anthropic",
)
```

This matters for tools built specifically on the Anthropic SDK: they can point at ClaudeN without any adapter.

Why route through one endpoint#

• One key, one balance, one usage log — instead of three provider accounts.
• Model comparison in minutes — change a string, not your stack.
• Payment that works where you live — top up with USDT or PayPal; no overseas credit card required.
• Free to try — every new account starts with a $5 trial credit.

Get started in five minutes#

Create an account, copy your key, and change one line in code you already have. If the result is not what you hoped, you have lost five minutes and none of your money — the trial credit covers the experiment. Get your API key and try the base_url swap today.