English

auth
cli
ai

What is CLI Auth and the common methods used today

CLI auth is becoming central to modern developer workflows. Logto supports all major CLI authentication methods.

Guamian

Product & Design

11/28/20253 min read

Stop wasting weeks on user auth

Launch secure apps faster with Logto. Integrate user auth in minutes, and focus on your core product.

Get started

Modern developer workflows rely heavily on command-line tools. From deploying cloud services to running AI agents or managing infrastructure, the CLI has become one of the most powerful interfaces for engineers. But behind every deploy, auth, or run command, there is a critical requirement:

The CLI must know who you are.

This is where CLI auth comes in.

In this article, we’ll break down what CLI auth means, why it matters, and the common authentication methods used across today’s developer ecosystem.

What is CLI Auth?

CLI auth (Command Line Interface authentication) refers to the mechanism a CLI uses to verify the identity of the person or service running commands.

It allows the CLI to:

authenticate the user
obtain short-lived and long-lived tokens
securely access backend APIs
maintain a persistent login session

If browsers rely on cookies and sessions, CLIs rely on tokens stored locally, combined with OAuth or other standardized auth flows.

In short, CLI auth gives the terminal its own login system so it can safely act on behalf of the user.

Why CLI auth is needed

CLI auth solves several real-world problems:

Identity — The API backend needs to know who is issuing commands.
Security — Developers shouldn’t paste raw secrets into terminals or scripts.
Token lifecycle — CLIs require short-lived access tokens with auto-refresh.
User convenience — Once authenticated, developers shouldn’t need to repeatedly log in.
Support for automation — CI/CD pipelines need machine-friendly tokens.

As CLIs grow in capability—especially with AI-driven tools—the need for robust and secure authentication becomes even more important.

Common CLI auth methods

Different platforms use different CLI auth methods depending on security requirements, UX needs, and infrastructure design. Below are the most widely used methods in modern developer tools.

1. OAuth 2.0 Device Code Flow (Most common method)

This is the industry-standard flow used by:

GitHub CLI
AWS SSO
Azure CLI
Vercel CLI
OpenAI CLI
Many AI-native runtimes

How it works

CLI calls the identity provider to request a device code.
User is asked to visit a URL and enter a short verification code.
Browser handles login (password, passkey, SSO).
After approval, the CLI receives tokens (access + refresh).
CLI stores tokens locally and uses them for future commands.

Why it’s popular

Works everywhere (local, SSH, containers).
Strong security properties.
No need to type passwords into terminals.
Supports MFA, passkeys, and enterprise SSO.

Device Code Flow is the default for modern developer tooling because it balances security, flexibility, and user experience.

2. Localhost Redirect OAuth Flow

Used by tools that want a smoother login experience.

How it works

CLI starts a tiny local server on a random port.
Browser opens automatically.
After login, the identity provider redirects back to http://localhost:xxxx/callback.
CLI receives the OAuth tokens and closes the local server.

Pros

High-quality user experience.
No copy-paste step.

Cons

Not ideal for remote shells or cloud environments.
Requires the ability to bind localhost ports.

Common in GUI-friendly CLIs or dev tools that want “one-click login.”

3. API keys / Personal access tokens (Legacy but still common)

Some CLIs allow developers to paste an API key or personal access token.

Example

Pros

Simple.
Easy to automate.

Cons

Lower security.
No MFA.
Hard to rotate.
Tokens often have broad permissions.

Most modern platforms are moving away from this model or restricting it to machine-use only.

4. Client Credentials (OAuth2 Client Credentials Flow)

This is the standard way for services and CI/CD jobs to authenticate without user interaction.

Auth providers issue:

client_id
client_secret

The service exchanges them for an access token:

Characteristics

No user involvement
No browser required
Short-lived access tokens
Ideal for backend-to-backend or CI systems
Integrates cleanly with OAuth2 and RBAC

This is the most widely supported automation auth method across all identity providers.

5. Username + Password input (Rare today)

Typing credentials directly into a CLI:

This method is outdated and not recommended because:

password input risks leakage
no MFA support
cannot integrate with SSO
poor audibility

Modern tools almost never use this except in offline or legacy enterprise environments.

How CLIs store tokens

Most CLIs store tokens in:

Preferred

macOS Keychain
Windows Credential Manager
Linux Keyring

Fallback

encrypted local files under ~/.config/toolname
JSON or TOML config files

Tokens must be:

short-lived
refreshable
revocable
scoped with roles and permissions

A well-designed token lifecycle is foundational for CLI auth security.

Which method should you use?

If you’re designing a CLI:

Scenario	Best auth method
Human logging in locally	Device Code Flow
Human with GUI needs	Localhost OAuth redirect
CI/CD	Client credential flow
Quick prototype	API keys
Enterprise SSO required	Device Code Flow

Device Code Flow is the modern default because it works everywhere and inherits the security of the browser.

Summary

CLI auth provides the identity foundation behind modern command-line tools.

It allows developers to authenticate securely, obtain tokens, and interact with cloud services or AI runtimes without exposing sensitive credentials.

The most common CLI auth methods include:

OAuth Device Code Flow
Localhost OAuth Redirect Flow
API keys / Personal Access Tokens
Client credential flow for CI/CD
Legacy username/password (rare today)

As developer tooling becomes more AI-driven and more work moves into the terminal, CLI auth is becoming a core part of modern identity infrastructure. Logto supports all major CLI auth patterns, with Device Code Flow currently in progress.

👉 Get started with Logto

Try Logto Cloud for free

What is CLI Auth?#

Why CLI auth is needed#

Common CLI auth methods#

1. OAuth 2.0 Device Code Flow (Most common method)#

2. Localhost Redirect OAuth Flow#

3. API keys / Personal access tokens (Legacy but still common)#

4. Client Credentials (OAuth2 Client Credentials Flow)#

5. Username + Password input (Rare today)#

How CLIs store tokens#

Preferred#

Fallback#

Which method should you use?#

Summary#

What is CLI Auth?#

Why CLI auth is needed#

Common CLI auth methods#

1. OAuth 2.0 Device Code Flow (Most common method)#

2. Localhost Redirect OAuth Flow#

3. API keys / Personal access tokens (Legacy but still common)#

4. Client Credentials (OAuth2 Client Credentials Flow)#

5. Username + Password input (Rare today)#

How CLIs store tokens#

Preferred#

Fallback#

Which method should you use?#

Summary#

What is CLI Auth?

Why CLI auth is needed

Common CLI auth methods

1. OAuth 2.0 Device Code Flow (Most common method)

2. Localhost Redirect OAuth Flow

3. API keys / Personal access tokens (Legacy but still common)

4. Client Credentials (OAuth2 Client Credentials Flow)

5. Username + Password input (Rare today)

How CLIs store tokens

Preferred

Fallback

Which method should you use?

Summary

What is CLI Auth?

Why CLI auth is needed

Common CLI auth methods

1. OAuth 2.0 Device Code Flow (Most common method)

2. Localhost Redirect OAuth Flow

3. API keys / Personal access tokens (Legacy but still common)

4. Client Credentials (OAuth2 Client Credentials Flow)

5. Username + Password input (Rare today)

How CLIs store tokens

Preferred

Fallback

Which method should you use?

Summary