Yahoo! launched Yahoo Desktop Search software in January 2005 using technology from X1.
Yahoo’s search program was definitely superior than competing products from Google or MSN because it supported many more file-types and would let you preview files even without the associated application.
Yahoo’s desktop tool was good enough that it won the editors’ choice award at PC Magazine but unfortunately, the product never picked up – Yahoo! silently abandoned further development and took the software offline.
Nobody noticed this because Windows inbuilt just got much better or people shifted to other good desktop search software like Google Desktop or Copernic.
X1 did release a free consumer version but seems to have disappeared as well.