vsftpd is an FTP server, or daemon.  The "vs" stands for Very Secure.
Obviously this is not a guarantee, but a reflection that I have written
the entire codebase with security in mind, and carefully designed the program
to be resilient to attack.

Recent evidence suggests that vsftpd is also extremely fast (and this is
before any explicit performance tuning!)  In tests against wu-ftpd, vsftpd
was always faster, supporting over twice as many users in some tests.