AutoStitch is pretty much where it all began
http://www.cs.ubc.ca/~mbrown/autostitch/autostitch.html
Quote "The version of AutoStitch on this website is a demo only. Individuals or companies are free to use images that they generate using the demo version of AutoStitch without restriction or royalties so long as they acknowledge the use of AutoStitch in such works. A commercial license to AutoStitch provides access to the patent, source code, technical support and updates."
Autopano Pro is amazing, but it is 99 Euros
http://www.autopano.net/
With out registering it works, but puts a watermark on the output image.
Just make sure you have the focal length right in the images you feed it, or force override to the correct value (e.g C8+f6.3 reducer 2032*0.63=1280mm)