Bearer Token Authentication is a popular security mechanism used in modern APIs. The client sends a token with every request, usually in the HTTP Authorization header, to access secured resources.
? Key Concepts
Stateless authentication
Access token represents user identity
Token sent with every request
Commonly used with REST APIs
? Syntax / Theory
The token is included in the request header using the Authorization scheme:
Authorization Header Format:
Authorization: Bearer <token>
? Code Example(s)
? View Code Example
// Sending a Bearer token using JavaScript fetch API
fetch("https://api.example.com/user/profile", {
headers: {
Authorization: "Bearer YOUR_ACCESS_TOKEN"
}
})
.then(response => response.json())
.then(data => console.log(data));
? Live Output / Explanation
Expected Behavior
If the token is valid, the server responds with protected data. If invalid or missing, the server returns 401 Unauthorized.
? Interactive Example / Flow
Typical Bearer Token flow:
User logs in with credentials
Server issues an access token
Client stores token securely
Client sends token in Authorization header
Server validates token on every request
? Token Flow Simulator
Current State: No Token (Logged Out)
SystemSimulator ready. Please login to generate a token.
? Use Cases
RESTful APIs
Single Page Applications (SPA)
Mobile app backends
Microservices authentication
✅ Tips & Best Practices
Always use HTTPS with bearer tokens
Set token expiration time
Do not store tokens in plain text
Use refresh tokens for long sessions
? Try It Yourself
Create a sample API endpoint that checks Authorization header