The Microsoft (r) Windows (r) based TFTP server previously provided by Cisco Systems has been discontinued and is no longer supported by Cisco Systems. Persons still using the server should consider replacing it with any of the high quality freeware and shareware TFTP servers. As a historical note, the Cisco TFTP server was released to customers in 1995 and at a time when no other freely available TFTP servers existed.
Today, there are many TFTP servers available, can be easily found by searching for "tftp server" on your favorite internet search engine. Cisco does not specifically recommend any particular TFTP implementation.
It is also useful to note that modern versions of IOS also support the use of FTP instead of TFTP for loading of images or configuration files. Use of FTP overcomes a number of inherent limitations of TFTP including a lack of security and a 16 megabyte file size limitation.