ComPDFKit
ComPDFKit enable developers to integrate PDF Annotations and Format Conversion, Digital Signature, Smart Forms, OCR, Redaction, and more in to their applications on Windows, macOS, iOS, Android, and the web through their PDF SDKs. Their aim is to offer the most comprehensive library to shorten the project development cycle and to continuously improve their SDK products to meet developer's future requirements as they change and projects evolve.
Jugaad
RadaeePDF SDK is a great PDF rendering and manipulation tool for developers. If you develop mobile or desktop applications the RadaeePDF SDK framework is the "Swiss Army knife" to handle PDF files. More than 6,000 applications are running the SDK on Android, iOS and Microsoft Windows UWP.
Big Faceless Organization (BFO)
Big Faceless Organization (BFO) develop Java APIs for working with PDF documents and graphs. Established in 1998, BFO has clients in over 50 different countries. Clients include, Amazon, Oracle, Siemens, VW, and Harvard University, as well as 50% of the top 30 banks in the World.