LLMs2API

OpenAI-compatible API gateway for ChatGPT, DeepSeek, Qwen, Claude & Gemini using browser automation

A unified OpenAI-compatible API gateway for multiple AI chat services including ChatGPT, DeepSeek, Qwen, Claude, and Gemini.

This solution enables seamless integration with popular AI platforms through a standardized REST API interface, leveraging browser automation to interact with web-based chat interfaces.

Overview

This project provides local API servers that expose OpenAI-compatible endpoints for various AI chat services. By utilizing Playwright for browser automation, it captures real-time streaming responses and delivers them through a familiar API format.

Key Features

OpenAI-Compatible API - Drop-in replacement for OpenAI SDK integrations
Multi-Provider Support - ChatGPT, DeepSeek, Qwen, Claude, and Gemini in one solution
Real-Time Streaming - Server-Sent Events (SSE) support for streaming responses
Image Generation - Nano Banana (Gemini) and Qwen image generation support
Concurrent Request Handling - Dynamic page pool supporting up to 10 parallel requests
Session Persistence - Automatic browser state management for seamless authentication
Stateless Architecture - Each request initiates a fresh conversation

Architecture

┌──────────────────┐     ┌──────────────────┐     ┌──────────────────┐
│   Application    │────▶│   API Gateway    │────▶│  Browser Engine  │
│  (Your Client)   │     │   (Node.js)      │     │   (Playwright)   │
└──────────────────┘     └──────────────────┘     └──────────────────┘
                                                           │
                                                           ▼
                                                  ┌──────────────────┐
                                                  │   AI Platform    │
                                                  │ (ChatGPT, etc.)  │
                                                  └──────────────────┘

The gateway intercepts network traffic to capture streaming responses directly, ensuring accurate and efficient data transmission.

Project Structure

├── chatgpt/               # ChatGPT Gateway (Port 3003)
│   ├── server.js
│   ├── package.json
│   └── browser-state.json
│
├── deepseek/              # DeepSeek Gateway (Port 3000)
│   ├── server.js
│   ├── package.json
│   └── browser-state.json
│
├── qwen/                  # Qwen Gateway (Port 3001)
│   ├── server.js
│   ├── package.json
│   └── browser-state.json
│
├── claude/                # Claude Gateway (Port 3002)
│   ├── server.js
│   ├── package.json
│   └── browser-state.json
│
├── gemini/                # Gemini Gateway (Port 3004)
│   ├── server.js
│   ├── package.json
│   └── browser-state.json
│
└── README.md

Installation

Prerequisites

Node.js 18.x or higher
Chromium browser (automatically installed by Playwright)

Setup

Navigate to the desired provider directory and install dependencies:

cd chatgpt  # or deepseek, qwen, claude, gemini
npm install

Launch

node server.js

Note: On first launch, a browser window will open for authentication. Complete the login process manually. Session credentials are automatically persisted for subsequent runs.

Service Configuration

Provider	Port	API Key	Base URL
ChatGPT	3003	`sk-chatgpt`	`http://localhost:3003/v1`
DeepSeek	3000	`sk-deepseek`	`http://localhost:3000/v1`
Qwen	3001	`sk-qwen`	`http://localhost:3001/v1`
Claude	3002	`sk-claude`	`http://localhost:3002/v1`
Gemini	3004	`sk-gemini`	`http://localhost:3004/v1`

API Reference

Endpoints

Method	Endpoint	Description
GET	`/health`	Service health check
GET	`/v1/models`	List available models
POST	`/v1/chat/completions`	Generate chat completion
POST	`/v1/images/generations`	Generate image (Qwen, Gemini)

Available Models

ChatGPT

Model ID	Description
`gpt-5.1`	GPT-5.1 (Default)

DeepSeek

Model ID	Description
`deepseek-v3.2`	Standard model
`deepseek-v3.2-thinking`	Enhanced reasoning mode
`deepseek-v3.2-search`	Web search enabled
`deepseek-v3.2-thinking-search`	Reasoning + Search

Qwen

Model ID	Description
`qwen3-max`	Standard model
`qwen3-max-thinking`	Enhanced reasoning mode
`qwen3-max-search`	Web search enabled
`qwen3-max-thinking-search`	Reasoning + Search
`qwen3-image`	Image generation
`qwen3-coder`	Code-optimized model
`qwen3-vl-235b`	Vision-language model (235B)
`qwen3-vl-32b`	Vision-language model (32B)

Claude

Model ID	Description
`claude-sonnet-4.5`	Claude Sonnet 4.5
`claude-haiku-4.5`	Claude Haiku 4.5

Gemini

Model ID	Description
`gemini-preview`	Gemini 3 Preview (Rapide) - Fast responses
`gemini-reasoning`	Gemini 3 Reasoning (Raisonnement) - Enhanced reasoning
`gemini-pro`	Gemini 3 Pro - Advanced capabilities
`nano-banana`	🍌 Nano Banana - Image generation with Preview
`nano-banana-pro`	🍌 Nano Banana Pro - Image generation with Pro

Gemini Image Generation: Use nano-banana or nano-banana-pro models to generate images. The response includes base64-encoded image data that can be displayed directly.

Gemini Web UI

The Gemini gateway includes a built-in chat interface for testing:

Start the Gemini server: cd gemini && node server.js
Open gemini/chat.html in your browser
Features:
- Model selection (all 5 models)
- Streaming toggle
- Markdown rendering
- Image display for Nano Banana responses
- Connection status indicator

Usage Examples

Python (OpenAI SDK)

from openai import OpenAI

# Initialize client
client = OpenAI(
    base_url="http://localhost:3003/v1",
    api_key="sk-chatgpt"
)

# Standard completion
response = client.chat.completions.create(
    model="gpt-5.1",
    messages=[
        {"role": "user", "content": "Explain quantum computing"}
    ]
)
print(response.choices[0].message.content)

# Streaming completion
stream = client.chat.completions.create(
    model="gpt-5.1",
    messages=[{"role": "user", "content": "Write a short story"}],
    stream=True
)
for chunk in stream:
    if chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="", flush=True)

cURL

# Standard request
curl -X POST http://localhost:3003/v1/chat/completions \
  -H "Authorization: Bearer sk-chatgpt" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.1",
    "messages": [{"role": "user", "content": "Hello"}],
    "stream": false
  }'

# Streaming request
curl -X POST http://localhost:3003/v1/chat/completions \
  -H "Authorization: Bearer sk-chatgpt" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.1",
    "messages": [{"role": "user", "content": "Hello"}],
    "stream": true
  }'

JavaScript

const response = await fetch("http://localhost:3003/v1/chat/completions", {
  method: "POST",
  headers: {
    "Authorization": "Bearer sk-chatgpt",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    model: "gpt-5.1",
    messages: [{ role: "user", content: "Hello" }],
    stream: false
  })
});

const data = await response.json();
console.log(data.choices[0].message.content);

PowerShell

$headers = @{
    "Authorization" = "Bearer sk-chatgpt"
    "Content-Type" = "application/json"
}

$body = @{
    model = "gpt-5.1"
    messages = @(
        @{ role = "user"; content = "Hello" }
    )
    stream = $false
} | ConvertTo-Json

$response = Invoke-RestMethod -Uri "http://localhost:3003/v1/chat/completions" `
    -Method POST -Headers $headers -Body $body

$response.choices[0].message.content

Gemini Examples

# Text generation with Gemini Preview
curl -X POST http://localhost:3004/v1/chat/completions \
  -H "Authorization: Bearer sk-gemini" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-preview",
    "messages": [{"role": "user", "content": "Explain quantum computing"}]
  }'

# Image generation with Nano Banana
curl -X POST http://localhost:3004/v1/images/generations \
  -H "Authorization: Bearer sk-gemini" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "nano-banana",
    "prompt": "A cat astronaut floating in space"
  }'

# Image generation via chat endpoint
curl -X POST http://localhost:3004/v1/chat/completions \
  -H "Authorization: Bearer sk-gemini" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "nano-banana-pro",
    "messages": [{"role": "user", "content": "Generate an image of a sunset over mountains"}]
  }'

# PowerShell - Gemini text request
$response = Invoke-RestMethod -Uri "http://localhost:3004/v1/chat/completions" `
  -Method POST `
  -Headers @{"Authorization"="Bearer sk-gemini"; "Content-Type"="application/json"} `
  -Body '{"model":"gemini-preview","messages":[{"role":"user","content":"Hello"}]}'

$response.choices[0].message.content

Environment Variables

Variable	Description	Default
`PORT`	Server listening port	Provider-specific
`AUTH_TOKEN`	API authentication key	Provider-specific
`HEADLESS`	Run browser in headless mode	`false`
`MAX_PAGES`	Maximum concurrent browser pages	`10`

Example

PORT=8080 HEADLESS=true MAX_PAGES=20 node server.js

Concurrency Model

The gateway implements a dynamic page pool for handling concurrent requests:

Requests are assigned to available browser pages
New pages are created on-demand up to MAX_PAGES limit
Idle pages are automatically recycled after 60 seconds
Minimum of 1 page is always maintained

Troubleshooting

Issue	Solution
Authentication required	Complete login in browser window on first run
Empty response	Verify login status; check browser window
Port in use	Change port via `PORT` environment variable
Session expired	Delete `browser-state.json` and re-authenticate
Gemini response truncated	Response parsing issue - check server logs
Nano Banana image blank	Wait longer for image to render (5s default)

Security Considerations

API keys are local identifiers, not transmitted externally
Browser sessions contain authentication tokens - secure browser-state.json appropriately
Intended for local development and personal use

License

This project is provided for educational and personal use. Users are responsible for compliance with respective AI provider terms of service.

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LLMs2API

Overview

Key Features

Architecture

Project Structure

Installation

Prerequisites

Setup

Launch

Service Configuration

API Reference

Endpoints

Available Models

Gemini Web UI

Usage Examples

Python (OpenAI SDK)

cURL

JavaScript

PowerShell

Gemini Examples

Environment Variables

Example

Concurrency Model

Troubleshooting

Security Considerations

License

FilesExpand file tree

README.md

Latest commit

History

README.md

File metadata and controls

LLMs2API

Overview

Key Features

Architecture

Project Structure

Installation

Prerequisites

Setup

Launch

Service Configuration

API Reference

Endpoints

Available Models

Gemini Web UI

Usage Examples

Python (OpenAI SDK)

cURL

JavaScript

PowerShell

Gemini Examples

Environment Variables

Example

Concurrency Model

Troubleshooting

Security Considerations

License