I've tried my hand at creating a truly software agnostic mosaic planner. It is web based, and will generate a fake star field fits file for each panel of the mosaic, allowing you to use the fits file in any software that will solve and slew.
It is pretty self-explanatory, but the idea is that you enter your imaging setup, then choose a target, setup a mosaic, and then download the fits files to use.
Please let me know what you think.

mosaic.darkdragons.space/
 

Outstanding work as usual Rick, bravo! Simple & beautiful!

Wow, truely impressive!

I see the FITS files are "binned" - I wonder if it would be possible to use them (at full scale) as alignment reference for stacking, to make the parts fit perfectly together?

Yeah, I made the decision to "bin" them artificially to make download sizes smaller. I might add a download button for a single full size fits file that includes the entire mosaic to use as a reference image for stacking.

nice work, thanks a lot for sharing it

Nice work! It might be desirable to include the center coordinates (J2000) for each panel in the section of the web form where the view/download info is located. That info comes in handy on occasion. Otherwise, great as is.

This is excellent - well done!

Very well done - good work!