Adxv
Visualizing XDS data reduction
The latest beta versions of ADXV (from http://www.scripps.edu/~arvai/adxv/) can read spot files (whose name ends with .adx) and display them together with the frames.
These spot files can be written by generate_adx. In adxv's file selection window, it is useful to change the filename pattern from e.g. "*.cbf" to just "*" which then gives you the possibility to load frames and spot files at will.
If using ADXV on a NoMachine (NX) desktop, it is useful to know that one needs the -nopixmap commandline option if the frame is not correctly displayed (I found that the zoom window still does not display correctly).