TFTPD32 is free, open-source TFTP server that is also includes a variety of different services, including DHCP, TFTP, DNS, and even syslog and functions as a TFTP Client as well.
TFTPD32 also comes as a x64 version that gets installed as a windows service.
This server is fully compatible with all the TFTP option support including tsize, blocksize and timeout to give you the best performance when transferring files back and forth.
Official Site and Download Links
Check out the official site for more information: