This is a public service announcement for people uploading their documents post-ITA.
Never use an unsecured online service to merge, resize, or clip PDFs of your sensitive personal information. Doing so would be exposing your personal information (passport, visas, transcripts, employment information, etc) to the world in a convenient package.
Instead, consider using free software that you can download to your computer and manipulate the files offline. I used pdfsam, which I found to provide all the necessary functionality for the purpose of uploading a single PDF of appropriate size during eAPR process.
The best is to use Mac for Merging and others stuff ad usually they come with Full Version of Adobe and Microsoft.
However, you can alternatively download a trial version of phantom PDF from Foxit or use Adobe Pro to do this. They are secure and performance is much more better than small PDF or other online tools.