What is htpasswd?
htpasswd is a command tool of the open-source HTTP server Apache HTTPD used to generate password files for HTTP basic authentication.
What are the differences in encryption methods?
MD5: Uses MD5 to encrypt passwords. This is the default encryption method on Windows, Netware, and TPF.
crypt: Uses crypt() to encrypt passwords. This is the default on platforms other than Windows, Netware, and TPF. While it can be supported on all platforms by htpasswd, it is not supported by the HTTPD server on Windows, Netware, and TPF.
SHA: Uses SHA to encrypt passwords. It is designed for easy transfer or migration to systems using LDAP Directory Interchange Format (LDIF) in Netscape.
plain: No encryption, uses plain text passwords. While htpasswd can create such passwords on all platforms, HTTPD only supports plain text passwords on Windows, Netware, and TPF.
Why make it online?
If we are not using an Apache server, such as Nginx, we may not have this command-line tool on hand to generate password files. Having an online version makes it convenient for server administrators to use.