Clone Download Killer is an internet tool help you check identify of URL before really download it. CDK would check the duplicate of file name , file size and content snippet. CDK check files with very high speed , in general , within 5 seconds you could see whether you had download the file before . CDK also monitor the click in Internet Explorer , as you click a file type like ".exe;.Zip;.Rar..." , I would automatically check this url , find duplicate files in local database and show the report to you. CDK fully support Internet Explorer,FlashGet,NetAnts,Go!Zilla,ReGet,GetRight, Download Accelerator, monitor the download from these software and add downloaded files into my local database for future comparing.