How to Configure Claude Code with a Custom API Key

When starting Claude Code, it first looks impossible to set a custom API key. You have two options:

Claude account with subscription - Pro, Max, Team, or Enterprise
Anthropic Console account - API usage billing

However, there is a hidden, third option, which is buried deep in the documentation and is usually the most-wanted authentication method by developers working for companies, because they are usually granted an Anthropic API key only, without a Console account. Here's what you need to do.

Create a file named settings.json in one of the following locations:

In your home directory
- macOS: ~/.claude/settings.json
- Windows: %USERPROFILE%\.claude\settings.json
- Linux: ~/.claude/settings.json
In your project directory's root
- ./.claude/settings.json

Add the following content to the file:

.claude/settings.json

{
  "apiKeyHelper": "echo <the-api-key-you-want-to-use>"
}

This file is compatible with macOS, Windows, and Linux.

Restart Claude Code, and you should be able to use it without being asked to log in.