Overview
Gemini CLI requires authentication with your Google account to access Google’s Gemini AI services. The authentication process is guided and happens automatically during your first launch or anytime authentication is required.Authentication Flow
The authentication setup occurs in two main steps, as documented in the installer (lines 122-128):Theme Selection
First, Gemini CLI will prompt you to select a color theme for the CLI interface.What to do:
- Use arrow keys to browse available themes (if multiple options are shown)
- If you have no preference, simply press Enter to use the default theme
- This is purely a visual preference and doesn’t affect functionality
Authentication Method Selection
Next, you’ll be asked to choose how you want to authenticate.What to do:
- “Login with Google” should be pre-selected
- Press Enter to confirm
- This is the standard and recommended authentication method
Google Account Login
After selecting “Login with Google”, your default web browser will automatically open.What to do:
- Your browser opens to a Google authentication page
- Follow the on-screen instructions
- Sign in with your Google Account credentials
- Grant the requested permissions to Gemini CLI
- The browser will confirm successful authentication
Important Notes from the Installer
The installer provides this guidance (translated from lines 120-128):After launch, in the opened PowerShell, complete the following settings once:
-
Theme Selection (Select Theme)
- This is a color setting. If you have no preference, just press [Enter].
-
Authentication Method Selection (Select Auth Method)
- Select “Login with Google” (it should already be selected) and press [Enter].
-
Browser Login
- Your browser will open. Follow the on-screen instructions to log in with your Google Account.
Authentication Method Details
Login with Google (Recommended)
This is the standard OAuth-based authentication method:- Security: Uses OAuth 2.0 protocol
- Convenience: One-time setup, credentials stored securely
- Access: Full access to your Gemini AI quota and features
- Browser-based: Requires a web browser for initial authentication
The installer specifically recommends using “Login with Google” as the authentication method. This should be pre-selected when you reach the authentication prompt.
What Gets Stored?
After successful authentication:- Tokens are saved locally on your computer
- No passwords are stored by Gemini CLI
- Credentials persist across sessions - you won’t need to re-authenticate each time
- Secure storage uses your operating system’s credential management
When Authentication is Required
You’ll need to authenticate:- First Launch: When you first install and run Gemini CLI
- Token Expiration: If your authentication token expires (rare)
- After Logout: If you manually log out from Gemini CLI
- New Installation: If you reinstall or move to a different computer
Troubleshooting Authentication
Browser Doesn’t Open Automatically
Solution:- Check that you have a default web browser configured
- Look in the PowerShell window for a URL
- If a URL is displayed, manually copy and paste it into your browser
- Complete the authentication in the browser
Browser Opens But Shows Error
Possible causes:- No internet connection: Verify your network connectivity
- Firewall blocking: Check firewall settings allow browser access to Google services
- Proxy issues: If behind a corporate proxy, ensure it’s properly configured
“Authentication Failed” Message
Solution:- Ensure you completed the entire browser flow
- Check that you granted all requested permissions
- Try the authentication process again
- Verify your Google Account is active and accessible
Theme Selection Doesn’t Appear
This is normal if:- Gemini CLI is already configured
- You’re not running Gemini CLI for the first time
- Configuration was completed in a previous session
Already Authenticated But Need to Re-authenticate
To log out and re-authenticate:- Look for Gemini CLI’s logout command (if available)
- Or delete stored credentials manually
- Restart Gemini CLI to trigger the authentication flow again
After Authentication
Once authenticated successfully:Verify Authentication
Try a simple command to verify everything works:If authenticated correctly, you should get a response from Gemini AI.
Close and Reopen
You can close the PowerShell window. Next time you use Gemini CLI, you won’t need to authenticate again.
Use the Desktop Shortcut
From now on, use the desktop shortcut to launch Gemini CLI anytime - no re-authentication required.
Security Best Practices
- Keep tokens private: Don’t copy or share authentication tokens
- Use your own account: Each user should authenticate with their own Google Account
- Secure your computer: Keep your computer password-protected to protect stored credentials
- Corporate accounts: If using a work Google Account, ensure compliance with your organization’s policies
Google Account Requirements
You need:
- A valid Google Account (Gmail or Google Workspace)
- Internet connectivity during authentication
- Access to Gemini AI services (may depend on your region and account type)
- A web browser installed on your computer
Privacy Considerations
When you authenticate:- Gemini CLI gets access to make API calls to Gemini AI on your behalf
- Your queries and responses are processed by Google’s Gemini service
- Review Google’s Gemini AI privacy policy for data handling information
- Check what permissions you’re granting during the OAuth flow
Next Steps
After completing authentication:- Learn about the desktop shortcut for easy access
- Start using Gemini CLI features
- Explore available commands and capabilities