The tools are not necessary to display panoramas, but help you take advantage of features in the player.

http://www.krpano.com/tools/

kpreview.exe
example:  Generating a preview which is similar to a track image preview in QTVR.
kmaketiles.exe
example:  Making tiles of copies of the panorama at different resolutions for serving more details on demand ("multiresolution panoramas").  This includes the capability of jpeg compression as an option.
ktransform.exe
example:  Convert an equirectangular/spherical panorama to cube faces.

krpano.swf is the player