I am not aware of any TFTP server which can do so. However there are softwares using TFTP or other protocols to communicate to device and take a configuration back.
Cisco's free tool Cisco Network Assistant can take a backup of configurations too. Also another feasible option is to configure a EEM script on device and schedule it to run periodically to send configuration to simple TFTP server by using CLI command copy running-config tftp:.
**Rating Encourages contributors, and its really free. **
If I'm guessing correctly that you are looking for a low cost way to get automated backups, I suggest you look into standing up a RANCID installation. RANCID is an open source project that runs on (free) Linux and is designed to do just that - automatically back up configurations.
You could probably cobble something together yourself with scripting, EEM, etc. but I would discourage that approach (unless you're taking it on as a hobby). Other folks have trod that path and it leads to RANCID.
You can set it up to e-mail you when it can't reach devices, to tell you what what diffs (if any) were found, etc. If you get ambitious you can put a search front end on the CVS that RANCID stores its files in and make all your configs searchable from a browser page. Helpful in a larger network to answer quick question like "What device is a given IP address on?"
Of course the enterprise class tools like CiscoWorks and SolarWinds also do this for you. But if you had one of those, you wouldn't have to ask about tftp solutions.
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