API Authentication Methods Explained

Securing Your API

Authentication verifies who is calling your API. Here are the main methods, from simple to robust.

1. API Keys

GET /data
Header: X-API-Key: abc123

Simple, good for server-to-server. Not ideal for users.

2. JWT (JSON Web Tokens)

GET /profile
Header: Authorization: Bearer eyJhbGci...

// Token contains encoded user info + signature

Stateless and popular for user auth. The server verifies the signature.

3. OAuth 2.0

"Login with Google/GitHub." Delegates authentication to a trusted provider — no password handling.

Comparison

Method	Best for
API Key	Server-to-server
JWT	User sessions (SPAs)
OAuth 2.0	Third-party login

Best Practices

• Always use HTTPS.
• Set token expiration.
• Never put secrets in frontend code.

FAQs

Authentication vs Authorization?

Authentication = who you are; authorization = what you can do. More in our API Development section.

Where do I store JWTs?

HttpOnly cookies are safest; avoid localStorage for sensitive tokens.