TeeCaptcha is a small tool that renders Teeworlds styled captchas.
This tool comes with the MIT license (see file LICENSE). All images used are taken from Teeworlds and come with their own license, see Teeworlds-license.txt.
For help on using the software, call it with --help or -h.
The file TeeCaptcha was compiled on a 64 bit Debian system using gcc, I guess. To run, libpng needs to be installed.