4. Appendix: Issuing and Using API Keys

In the CLI and SDK steps up to this page, we authenticated using the login credentials from ant auth login. No API key was issued. This page explains how authentication works and how to issue and configure an API key when you need one.

No API Key Needed If You Are Logged In via the CLI

The ant CLI and the anthropic package (SDK) look for credentials in the following order of precedence:

1. The ANTHROPIC_API_KEY environment variable
2. The ANTHROPIC_AUTH_TOKEN environment variable
3. The login credentials saved by ant auth login (%APPDATA%\Anthropic on Windows, ~/.config/anthropic/ on macOS)

Therefore, on a machine where you have already run ant auth login, both the CLI and an SDK client created with a no-argument Anthropic() work as-is with no extra configuration. Token expiration is also refreshed automatically.

If you are unsure which credentials are being used, you can check with the following command.

Windows

./ant auth status

macOS

ant auth status

Caution

Environment variables take precedence over login credentials. If a stale ANTHROPIC_API_KEY is left in your environment variables (even an empty string), it will be used instead—so delete the environment variable if you want to authenticate with your login credentials.

When You Need an API Key

Use an API key instead of login credentials in situations like these:

• Running in environments where browser-based login is not possible, such as CI or servers
• Using only the SDK on a machine where ant is not installed
• Embedding into an application shared by your team

Issue an API Key

1. Select the “API keys” menu in the Console and click “Create key”.

   

   Note

   Make sure the workspace is set to “workshop”. API keys are issued per workspace and can only access that workspace’s resources.

2. Enter a name and click “Add”. Note down the displayed API key (a string starting with sk-ant-).

   

Use the API Key

Set it in the ANTHROPIC_API_KEY environment variable, and both the CLI and the SDK will use it automatically.

Windows

$env:ANTHROPIC_API_KEY = "YOUR_API_KEY_HERE"

macOS

export ANTHROPIC_API_KEY="YOUR_API_KEY_HERE"

Caution

This setting disappears when you close the window. To make it persistent, use “Edit environment variables” on Windows, or append it to ~/.zshrc on macOS. Avoid hard-coding the API key directly in your script’s source code.