Base64 is an encoding scheme that is used by "Basic Authentication" in order to transmit your username/password.
Unfortunately many websites today still use Basic authentication. In HTTP Basic authentication , the " password:username " is encoded in Base64 . Since it's not encrypted, it is almost the same as "cleartext" as it can be easily decoded with sites like the following (https://www.base64decode.org)! If you connected to a free web-service via Basic authentication and a bad actor captures that same network traffic they may be able to use that same username and password to log on to your banking website (if you use the same username and password on that site). You should either use "throw away" passwords for these open websites or only connect to websites via " HTTPS ".