What is JWT and how is it used securely in frontend applications?

Question

What is JWT and how is it used securely in frontend applications?

Answer

JWT (JSON Web Token) is a compact token format used for securely transmitting information between client and server.

A JWT contains:

• Header
• Payload
• Signature

Secure Usage

• Prefer storing tokens in HTTP-only cookies
• Avoid storing sensitive data in payload
• Use HTTPS always
• Implement token expiration and refresh strategy

fetch("/api/profile", {
  headers: {
    Authorization: `Bearer ${token}`,
  },
});

Key Points

• JWTs are stateless
• Avoid localStorage for sensitive tokens
• Always validate tokens on backend