jPDF Tweak is a Java GUI application that uses the iText library for manipulating PDF files.
Merge (selected pages of) multiple
PDF files, as if you printed them one after another
Rotate either all pages or Portrait/Landscape pages only (for PDFs that contain both orientations and should only contain one of them)
Scale all pages to a common size
Add another
PDF or a text as watermark
Add page numbers
Put n pages onto one page
Generate Booklets
Change Chapter Bookmarks (initial state, font style, text, destination)
Attach files
Add page transitions and delays for full-screen presentation
Set initial view when opened in a
PDF viewer
Change Title/Subject/Keywords/Author/Creator/Producer information
Encrypt with a password, set permissions
Add a digital signature
Burst pages to individual
PDF files
Compress/Decompress the
PDF file
And that all in around 800K file size, thanks to Proguard obfuscator that removed all unnecessary class files from the iText library.