<strong>API authentication</strong> is the process of verifying the identity of clients making API requests. Common methods include API keys, JWT tokens, and OAuth, each offering different levels of security and complexity.
The Building Access Analogy
API keys are like building keys (simple but if stolen, anyone can use). JWT is like a temporary badge (expires after time). OAuth is like showing ID to get a visitor pass (secure, delegated).
API Key (Building Key)
Simple access
JWT (Temporary Badge)
Time-limited access
OAuth (ID Verification)
Delegated access
Sends Credentials
Verifies Identity
Grants Access
Client provides credentials
API key, username/password, or OAuth token
Server validates
Checks if credentials are valid and not expired
Generate token (JWT)
Create signed token with user info and expiration
Client includes token
Send token in Authorization header with each request
Server verifies token
Validate signature and check expiration on each request
Wrong
"API keys are secure enough for everything"
Correct
API keys are <strong>simple but not secure for user authentication</strong>. Use JWT for user sessions and OAuth for third-party access. API keys are best for server-to-server communication.
Twitter API authentication:
You register your app and get API key + secret
Users authorize your app via OAuth
Twitter gives you an access token for that user
You include the token in API requests to access user data