What HTTP response codes do you know? How does 401 differ from 403?

Some common HTTP response codes:

• 200 OK — request successfully processed
• 201 Created — resource successfully created
• 400 Bad Request — invalid request
• 401 Unauthorized — authentication required
• 403 Forbidden — access denied
• 404 Not Found — resource not found
• 500 Internal Server Error — internal server error

Difference between 401 and 403:

• 401 Unauthorized means that the client is not authenticated or provided incorrect credentials. The server expects the client to authenticate first.

• 403 Forbidden means that the client is authenticated but does not have permission to access the resource. The server understands who the client is but denies access.

Example:

If a user is not logged in and tries to access a protected resource — the server will return 401. If a user is logged in but does not have permission for that resource — the server will return 403.