Claude Max API proxy

claude-max-api-proxy is a community tool that exposes your Claude Max/Pro subscription as an OpenAI-compatible API endpoint. This allows you to use your subscription with any tool that supports the OpenAI API format.

This path is technical compatibility only. Anthropic has blocked some subscription usage outside Claude Code in the past. You must decide for yourself whether to use it and verify Anthropic’s current terms before relying on it.

Why use this?

Approach	Cost	Best For
Anthropic API	Pay per token (~ $15/M input,$ 75/M output for Opus)	Production apps, high volume
Claude Max subscription	$200/month flat	Personal use, development, unlimited usage

If you have a Claude Max subscription and want to use it with OpenAI-compatible tools, this proxy may reduce cost for some workflows. API keys remain the clearer policy path for production use.

How it works

Your App → claude-max-api-proxy → Claude Code CLI → Anthropic (via subscription)
     (OpenAI format)              (converts format)      (uses your login)

The proxy:

Accepts OpenAI-format requests at http://localhost:3456/v1/chat/completions
Converts them to Claude Code CLI commands
Returns responses in OpenAI format (streaming supported)

Getting started

Install the proxy

Requires Node.js 20+ and Claude Code CLI.

npm install -g claude-max-api-proxy

# Verify Claude CLI is authenticated
claude --version

Start the server

claude-max-api
# Server runs at http://localhost:3456

Test the proxy

# Health check
curl http://localhost:3456/health

# List models
curl http://localhost:3456/v1/models

# Chat completion
curl http://localhost:3456/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-4",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

Configure FluffBuzz

Point FluffBuzz at the proxy as a custom OpenAI-compatible endpoint:

{
  env: {
    OPENAI_API_KEY: "not-needed",
    OPENAI_BASE_URL: "http://localhost:3456/v1",
  },
  agents: {
    defaults: {
      model: { primary: "openai/claude-opus-4" },
    },
  },
}

Built-in catalog

Model ID	Maps To
`claude-opus-4`	Claude Opus 4
`claude-sonnet-4`	Claude Sonnet 4
`claude-haiku-4`	Claude Haiku 4

Advanced configuration

Proxy-style OpenAI-compatible notes

This path uses the same proxy-style OpenAI-compatible route as other custom /v1 backends:

Native OpenAI-only request shaping does not apply
No service_tier, no Responses store, no prompt-cache hints, and no OpenAI reasoning-compat payload shaping
Hidden FluffBuzz attribution headers (originator, version, User-Agent) are not injected on the proxy URL

Auto-start on macOS with LaunchAgent

Create a LaunchAgent to run the proxy automatically:

cat > ~/Library/LaunchAgents/com.claude-max-api.plist << 'EOF'
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>com.claude-max-api</string>
  <key>RunAtLoad</key>
  <true/>
  <key>KeepAlive</key>
  <true/>
  <key>ProgramArguments</key>
  <array>
    <string>/usr/local/bin/node</string>
    <string>/usr/local/lib/node_modules/claude-max-api-proxy/dist/server/standalone.js</string>
  </array>
  <key>EnvironmentVariables</key>
  <dict>
    <key>PATH</key>
    <string>/usr/local/bin:/opt/homebrew/bin:~/.local/bin:/usr/bin:/bin</string>
  </dict>
</dict>
</plist>
EOF

launchctl bootstrap gui/$(id -u) ~/Library/LaunchAgents/com.claude-max-api.plist

Notes

This is a community tool, not officially supported by Anthropic or FluffBuzz
Requires an active Claude Max/Pro subscription with Claude Code CLI authenticated
The proxy runs locally and does not send data to any third-party servers
Streaming responses are fully supported

For native Anthropic integration with Claude CLI or API keys, see Anthropic provider. For OpenAI/Codex subscriptions, see OpenAI provider.

Anthropic provider

Native FluffBuzz integration with Claude CLI or API keys.

OpenAI provider

For OpenAI/Codex subscriptions.

Model selection

Overview of all providers, model refs, and failover behavior.

Configuration

Full config reference.

Overview

Concepts and configuration

Providers

Claude Max API proxy

Why use this?

How it works

Getting started

Built-in catalog

Advanced configuration

Links

Notes

Anthropic provider

OpenAI provider

Model selection

Configuration

​Why use this?

​How it works

​Getting started

​Built-in catalog

​Advanced configuration

​Links

​Notes

​Related

Anthropic provider

OpenAI provider

Model selection

Configuration

Why use this?

How it works

Getting started

Built-in catalog

Advanced configuration

Links

Notes

Related