Awesome
Sejda SDK (https://www.sejda.org)
Sejda SDK is a task oriented PDF editor SDK library written in Java.
Sejda SDK offers a set of "ready to go" manipulations implemented using SAMBox, a PDFBox fork that we maintain. Quick start: https://github.com/torakiki/sejda/wiki/Getting-Started
A full list of the available tasks: https://github.com/torakiki/sejda/wiki/Tasks
Sejda SDK open source
Is an open source Java library providing a set of PDF manipulation tasks
Sejda SDK PRO
Is a commercial Java library built on top of the open source library and providing additional PDF manipulation tasks
Sejda console PRO
sejda-console-pro is a commercial command line tool that can be used directly from the terminal or from your own code.
Get started: https://github.com/torakiki/sejda/wiki/Getting-Started
Web Interface
A web interface is available at https://sejda.com where the most commonly used tasks are available as online services:
Apply header/footer or page numbers to PDF pages
Desktop
Sejda SDK is the engine behind PDFsam Basic, a free and open source desktop application to split, merge, extract pages, rotate and mix PDF files
License
Sejda 1.x is licensed under Apache License, Version 2.0
Sejda 2.x and higher are licensed under GNU Affero Public License 3.0