In one of the projects that I am working on I needed a utility that would delete links from one file that were in another file. So, I quickly wrote one. Then I realized that the same utility would be useful for IP addresses and comments in addition to URL's. So I rewrote the Utility to handle those as well. The code is nothing fancy and is not multi threaded; the code is just down and dirty 'make it work' kludged code. No real attempt at optimization was made, and there was no real attempt at code reuse. In the 64 bit compilation I tested a 1.3 million link file against another 1.3 million link file in which there were only two shared urls. I also repeated this same test with IP's. With that many url's or IP's, the program took a couple of hours to complete. When tested against more realistic files of 100,000 plus url's or IP's, the program would complete in a few seconds to a few minutes dependent on the particulars of the files. Here are images: url/link deletion IP deletion Comment deletion Because I occasionally see people asking about this type of utility, I decided to make the source code and the executable available. The executables are in the Link_delete.rar\link_delete\link_delete\bin\x64\Release and the Link_delete.rar\link_delete\link_delete\bin\x32\Release and are named link_delete.exe. The "No separator" check box is specific to the project this was written for. This utility is written for dot net 4.5 and was written with Visual Studio 2013. The virus totals are: 64 bit executable: (0/54) https://www.virustotal.com/en/file/...5738026d6b38246896aef47a/analysis/1437520039/ 32bit executable: (0/55) https://www.virustotal.com/en/file/...630c62871fc99873afef7114/analysis/1437519876/ If you are interested, you may download the source and executables from: https://www.sendspace.com/file/hq00zk Have phun.