What is htpasswd?
htpasswd is a command-line utility of the open-source HTTP server Apache HTTPD, used for generating password files for HTTP Basic Authentication.
What are the differences in encryption methods?
MD5: Encrypts passwords using MD5. This is the default encryption method on Windows, Netware, and TPF.
crypt: Encrypts passwords using crypt(). This is the default on platforms other than Windows, Netware, and TPF. Although it is supported by htpasswd on all platforms, it is not supported by the httpd server on Windows, Netware, and TPF.
SHA: Encrypts passwords using SHA. It is designed for easy transition or migration to Netscape using LDAP Directory Interchange Format (ldif).
plain: Does not encrypt passwords, using plaintext instead. Although htpasswd can create such passwords on all platforms, the httpd backend only supports plaintext passwords on Windows, Netware, and TPF.
Why create an online version?
If we are not using an Apache server, such as nginx, we may not have this command-line tool at hand and would be unable to generate password files. An online version facilitates the use by server administrators.