OAuth 2.0: The Industry Standard Framework

OAuth 2.0: The Industry Standard Framework

OAuth 2.0 provides a comprehensive framework for API authentication and authorization, supporting various flow types for different scenarios. Rather than a single authentication method, OAuth 2.0 defines how clients obtain tokens and access protected resources. Understanding and implementing OAuth 2.0 correctly is essential for modern API security.

The Authorization Code flow, suitable for web applications, provides the highest security level. Clients redirect users to an authorization server, users authenticate and approve access, and clients exchange authorization codes for tokens. This flow keeps credentials away from client applications and supports fine-grained consent.

# Python Flask example of OAuth 2.0 Authorization Code flow
from flask import Flask, request, redirect
import requests

app = Flask(__name__)

CLIENT_ID = 'your_client_id'
CLIENT_SECRET = 'your_client_secret'
REDIRECT_URI = 'https://yourapp.com/callback'

@app.route('/login')
def login():
    auth_url = f"https://auth.example.com/authorize?client_id={CLIENT_ID}&response_type=code&redirect_uri={REDIRECT_URI}&scope=read:data"
    return redirect(auth_url)

@app.route('/callback')
def callback():
    code = request.args.get('code')
    
    token_response = requests.post('https://auth.example.com/token', data={
        'grant_type': 'authorization_code',
        'code': code,
        'client_id': CLIENT_ID,
        'client_secret': CLIENT_SECRET,
        'redirect_uri': REDIRECT_URI
    })
    
    tokens = token_response.json()
    access_token = tokens['access_token']
    # Store and use access_token for API requests

The Client Credentials flow serves machine-to-machine authentication where no user context exists. Clients authenticate directly with their credentials to obtain access tokens. This flow suits backend services, scheduled jobs, and system integrations. Security depends on protecting client credentials and implementing proper token scoping.