What is the difference between a JWT token and a regular authentication token?

JWT (JSON Web Token) is a standard token format that contains encoded payload data about the user and a signature for authenticity verification. A typical authentication token is often a random string (for example, a session identifier) stored on the server and linked to user data.

Main differences:

• Structure: JWT is a self-contained token that includes data and a signature, whereas a regular token is just a key linked to a session on the server.
• Verification: JWT can be verified without contacting the server (if a public key is available), while a regular token requires server verification.
• Data storage: JWT contains payload data (e.g., user ID, roles), whereas a regular token does not contain data, only an identifier.
• Security: JWT is signed and can be verified for integrity, but if encryption is not used, data is visible in plain text.

Example of JWT payload:

{
  "sub": "1234567890",
  "name": "Ivan Ivanov",
  "iat": 1516239022
}

In Go, the library github.com/dgrijalva/jwt-go is often used for working with JWTs.