lagp 1.0.0

Local OpenAI-compatible proxy using ChatGPT Plus via OAuth

LAGP — LLM Auth Gateway Proxy

A local OpenAI-compatible proxy powered by your ChatGPT Plus subscription — no API key required.

---

What is LAGP?

LAGP runs a local HTTP server on port 11434 that speaks the OpenAI API. Any tool that accepts a custom base URL — Cline, Cursor, Continue, Open WebUI, or your own scripts — can point to http://localhost:11434 and use your existing ChatGPT Plus account as the backend, at no extra cost.

Authentication happens once through a standard browser OAuth flow. The token is stored locally at ~/.lagp/auth.json and refreshed automatically.

Your tool (Cline, Cursor…)
        │  OpenAI API calls
        ▼
 http://localhost:11434   ← LAGP
        │  ChatGPT OAuth
        ▼
  chatgpt.com backend

---

Requirements

• Python 3.9+
• An active ChatGPT Plus (or higher) subscription
• A modern browser (for the one-time OAuth login)

---

Installation

From PyPI

pip install lagp

From source

git clone https://github.com/helvecioneto/lagp.git
cd lagp
pip install .

---

Usage

Start the server:

lagp

On the first run, a browser window opens automatically for login. Sign in with your OpenAI account and the token is saved. The server starts immediately after authentication.

On subsequent runs, the saved token is loaded and the server starts right away.

Configure your tool

Point any OpenAI-compatible client to the local server:

Setting	Value
Base URL	http://localhost:11434/v1
API Key	any non-empty string (e.g. lagp)

---

Available models

LAGP queries the ChatGPT backend at startup and lists the models your account can access. To see the live list at any time:

curl http://localhost:11434/v1/models

Typical models available with ChatGPT Plus:

Model	Notes
gpt-5.3-codex	Latest, recommended
gpt-5.2-codex	Previous generation
gpt-5.1-codex-max	High-capacity variant
gpt-5.1-codex-mini	Faster, lighter
gpt-5.2	General purpose

The list is fetched live from the API — new models appear automatically as OpenAI releases them.

---

Endpoints

Method	Path	Description
GET	/login	Start OAuth login flow
GET	/v1/models	List available models (OpenAI format)
POST	/v1/chat/completions	OpenAI-compatible chat completions
POST	/api/chat	Ollama-compatible chat (NDJSON)
GET	/api/tags	Ollama model discovery

---

Quick test

Check available models:

curl http://localhost:11434/v1/models

Send a chat message:

curl http://localhost:11434/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{"model": "gpt-5.3-codex", "messages": [{"role": "user", "content": "Hello!"}]}'

Use with the OpenAI Python SDK:

from openai import OpenAI

client = OpenAI(base_url="http://localhost:11434/v1", api_key="lagp")

response = client.chat.completions.create(
    model="gpt-5.3-codex",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(response.choices[0].message.content)

---

Running on a remote server

LAGP works great on headless remote servers (VPS, cloud instances, etc.). Because the OAuth provider only allows localhost as a valid redirect URI, you cannot authenticate directly on a remote machine through its public IP. There are three supported approaches.

---

Method 1 — Token sync (recommended)

Authenticate on your local machine and push the tokens automatically to the remote server over HTTP.

On the remote server, start LAGP in no-browser mode with a shared secret:

lagp --no-browser --sync-secret <your-secret>

On your local machine, run:

lagp --sync-to http://<server-ip>:11434 --sync-secret <your-secret>

A browser opens, you log in with your OpenAI account, and the tokens are pushed to the remote server automatically. From that point the remote server is fully authenticated.

Network requirement: port 11434 must be open on the remote server.

Note: --sync-secret is strongly recommended. Without it, anyone who can reach port 11434 could push arbitrary tokens to your server.

---

Method 2 — SSH tunnel

No configuration needed beyond SSH access. The tunnel makes the remote server's ports appear as local ports, so localhost redirect URIs work transparently.

Open two tunnels from your local machine:

ssh -L 11434:localhost:11434 -L 1455:localhost:1455 user@<server>

On the remote server (in another terminal or tmux):

lagp --no-browser

On your local machine, open in a browser:

http://localhost:11434/login

OAuth redirects to localhost:1455, which the tunnel forwards to the remote server. Tokens are saved on the server. Close the tunnel when done — lagp runs independently from that point.

Network requirement: only SSH (port 22) needs to be open.

---

Method 3 — Copy auth.json manually

If you have already authenticated locally, just copy the token file to the remote server:

scp ~/.lagp/auth.json user@<server>:~/.lagp/auth.json

Then start LAGP on the remote server:

lagp --no-browser

It will load the existing token and start immediately. Tokens refresh automatically, so this file stays valid until you explicitly log out.

---

Comparison

	Method 1 (sync)	Method 2 (SSH tunnel)	Method 3 (copy)
Requires open port	11434	22 only	22 only
Fully automated	✓	—	—
No extra tooling	✓	needs SSH tunnel	needs SCP
Works without local LAGP	—	—	✓

---

Re-authentication

Tokens expire eventually. To re-authenticate on a remote server, run either Method 1 or Method 2 again. The new token overwrites the old one at ~/.lagp/auth.json.

---

CLI reference

Flag	Default	Description
--port PORT	11434	Port for the proxy server
--callback-port PORT	1455	Port for the OAuth callback listener
--no-browser	off	Do not open a browser automatically
--sync-to URL	—	Push tokens to a remote LAGP after login
--sync-secret SECRET	—	Shared secret protecting the /auth/sync endpoint
--log-level LEVEL	INFO	Log verbosity: DEBUG, INFO, WARNING, ERROR

---

Token storage

The auth token is stored at ~/.lagp/auth.json on all platforms. To log out, delete this file and restart lagp.

---

License

MIT — see LICENSE.