Set up Claude Code with a RocketKey API key on Windows, macOS and Linux (ANTHROPIC_BASE_URL, settings.json, VS Code)

This page is the configuration reference: environment variables, settings.json and the VS Code extension. If you don't have a key yet, read Getting started first.

Every snippet below uses the placeholder key sk-rk-YOUR_KEY_HERE: replace it with your own key.

Before you start

• Claude Code is installed (the claude command runs in your terminal).
• If you ever signed in to Claude Code with an Anthropic account, type /logout in Claude Code first and remove any ANTHROPIC_API_KEY variable. The commands below already clear it in the current window.
• Claude Code's base URL has no /v1 at the end.

Option 1: environment variables (quickest)

Paste into your terminal, then run claude in the same window:

unset ANTHROPIC_API_KEY
export ANTHROPIC_BASE_URL='https://rocketkeyapi.indexes.social'
export ANTHROPIC_AUTH_TOKEN='sk-rk-YOUR_KEY_HERE'

Remove-Item Env:ANTHROPIC_API_KEY -ErrorAction SilentlyContinue
$env:ANTHROPIC_BASE_URL = 'https://rocketkeyapi.indexes.social'
$env:ANTHROPIC_AUTH_TOKEN = 'sk-rk-YOUR_KEY_HERE'

set ANTHROPIC_API_KEY=
set ANTHROPIC_BASE_URL=https://rocketkeyapi.indexes.social
set ANTHROPIC_AUTH_TOKEN=sk-rk-YOUR_KEY_HERE

The variables only last for that window. To keep them, add the export lines to ~/.bashrc / ~/.zshrc, or use option 2.

Option 2: settings.json (permanent)

Add the env block to ~/.claude/settings.json (Windows: %USERPROFILE%\.claude\settings.json). If the file already has content, merge just the env part:

{
  "env": {
    "ANTHROPIC_BASE_URL": "https://rocketkeyapi.indexes.social",
    "ANTHROPIC_AUTH_TOKEN": "sk-rk-YOUR_KEY_HERE"
  }
}

Claude Code extension for VS Code

Add to your VS Code settings.json (Command Palette → "Preferences: Open User Settings (JSON)"):

{
  "claudeCode.environmentVariables": [
    {
      "name": "ANTHROPIC_BASE_URL",
      "value": "https://rocketkeyapi.indexes.social"
    },
    {
      "name": "ANTHROPIC_AUTH_TOKEN",
      "value": "sk-rk-YOUR_KEY_HERE"
    }
  ]
}

Reload the VS Code window after saving.

Choosing a model

Claude Code picks models by its opus, sonnet and haiku slots. To pin a specific model, add ANTHROPIC_DEFAULT_SONNET_MODEL (or _OPUS_, _HAIKU_) with a model ID from the Models page. A wrong model ID causes error 404.

Check it works

In Claude Code, type /status: the base URL line must show RocketKey's address. Send a short question to make sure the key works.

Common errors

• 401 / Invalid API key: wrong or deleted key, or an old ANTHROPIC_API_KEY is still set. See error 401.
• 402 ExceededBudget: daily cap reached. See error 402.
• 429 / 529 overloaded: see error 429.