Documentation

OpusZen Docs

Anthropic-compatible API gateway providing Claude API access without waitlists. Drop-in replacement — just change your base URL.

Overview

OpusZen is an Anthropic-compatible API gateway providing Claude API access without waitlists. It works with Claude Code, Cursor, Windsurf, Cline, Roo Code, and any Anthropic SDK — just swap your base URL and go.

Zero-latency SSE streaming pass-through

Per-key budgets & rolling windows

Built-in web search & image analysis

Prompt caching — cache tokens are free

Quick Start

Prerequisites

Node.js 18+
OpusZen API key (from your admin or reseller)
Supported IDE: Claude Code, VS Code, Cursor, Windsurf, Cline, or Roo Code

Interactive Setup

Run the interactive setup wizard — it handles everything:

bash

npx opuszen

Or use the platform-specific setup scripts:

powershell

irm https://opuszen.com/setup.ps1 | iex

bash

curl -fsSL https://opuszen.com/setup.sh | bash

Manual Setup

If you prefer to configure manually, edit your settings file and set the following environment variables or config values:

json

{
 "env": {
 "ANTHROPIC_AUTH_TOKEN": "YOUR_API_KEY",
 "ANTHROPIC_BASE_URL": "https://opuszen.com"
 }
}

IDE Configuration

Claude CodeVS Code extension

Edit ~/.claude/settings.json

json

{
  "env": {
    "ANTHROPIC_AUTH_TOKEN": "YOUR_API_KEY",
    "ANTHROPIC_BASE_URL": "https://opuszen.com",
    "ANTHROPIC_MODEL": "Opus 4.8",
    "ANTHROPIC_SMALL_FAST_MODEL": "Haiku 4.5",
    "ANTHROPIC_DEFAULT_SONNET_MODEL": "Sonnet 4.6",
    "ANTHROPIC_DEFAULT_OPUS_MODEL": "Opus 4.8",
    "ANTHROPIC_DEFAULT_HAIKU_MODEL": "Haiku 4.5",
    "CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC": "1"
  },
  "hasCompletedOnboarding": true
}

Cursor

In Cursor settings, set Base URL and model:

Base URLhttps://opuszen.com/v1

Modelclaude-sonnet-4-6

Windsurf

In Windsurf settings, set the Base URL:

text

https://opuszen.com/v1

ClineRoo Code

Add to your VS Code settings.json with provider "anthropic", your base URL, and API key.

API Reference

Authentication

Pass your API key using either header:

http

x-api-key: YOUR_API_KEY

http

Authorization: Bearer YOUR_API_KEY

POST/api/v1/messages

Create a message. Set stream: true for Server-Sent Events with message_start, content_block_delta, and message_stop events.

json

{ "model": "claude-opus-4-8", "messages": [{ "role": "user", "content": "Hello" }], "max_tokens": 1024, "stream": false }

GET/api/v1/models

List all available models with context window information.

POST/api/v1/messages/count_tokens

Count tokens without sending a message.

json

{ "model": "claude-opus-4-8", "messages": [{ "role": "user", "content": "Hello" }] }

GET/api/key-status?key=YOUR_API_KEY

Check your key status, current usage, and rate limit windows.

Models

All models are Anthropic-compatible and work with standard Anthropic SDK calls. Just set the model ID in your requests.

Model	Model ID	Context	Type	Created

Built-in Tools

Web search and image analysis are available server-side — no client-side MCP setup or additional configuration required.

Web Search

Real-time web search powered by OpusZen. Use 3–5 focused keywords for best results.

http

POST /tools/web_search

json

{ "query": "latest Anthropic API updates 2026" }

Image Analysis

Analyze images via HTTP URLs, local file paths, or base64-encoded data. Max file size: 18MB.

http

POST /tools/understand_image

json

{ "image": "https://example.com/photo.jpg" }

Troubleshooting

Connection errors

Check the key is active and not expired on the Check Usage page.

Web search or image tools not firing

They are server-side and always on. If they seem inactive, the key is usually the problem, not the config.

Model not found

Use an exact ID from the models list above, or a friendly alias.

Rate limited

Your five-hour window may be spent. Check /api/key-status for the reset time.

Changes not applying

Restart the editor after any config change.

Cursor or Windsurf not routing

Make sure the URL you pasted ends in /v1.

Still stuck?

Contact your admin or reseller for key-specific support.