What is htpasswd?
htpasswd is a command tool of the open source http server apache httpd, used to generate http basic authentication password files.
What is the difference between the encryption methods?
MD5: Use MD5 to encrypt the password. On Windows, Netware and TPF, this is the default encryption method.
crypt: Encrypt passwords using crypt(). This is the default on platforms other than Windows, Netware and TPF. Although it is supported by htpasswd on all platforms, But it is not supported by httpd server on Windows, Netware and TPF.
SHA: Use SHA to encrypt passwords. It is for ease of transfer or porting to use LDAP Directory Interchange Format (ldif) Netscape.
plain: No encryption, use a plain text password. Although htpasswd can create such a password on all platforms, the httpd background is only available on Windows, Plain text passwords are supported on Netware and TPF.
Why should it be made online?
If we don't use the apache server, such as nginx, etc., we may not have this command line tool at hand, and we cannot generate a password file. The online version is convenient for server administrators to use.