iText for Java represents the next level of SDKs for developers that want to take advantage of the benefits PDF can bring. Equipped with a better document engine, high and low-level programming cap…

OFD Reader & Writer 开源的OFD处理库，支持文档生成、数字签名、文档保护、文档合并、转换、导出等功能，文档格式遵循《GB/T 33190-2016 电子文件存储与交换格式版式文档》。

Apache Freemarker

Offer comprehensive code samples and show how to integrate the ComPDFKit PDF SDK to build a PDF viewer and editor on Android.

ComPDFKit PDF API is organized around the REST standard and supports various programming languages with rich PDF features, including conversion, document editor, data extraction, and so forth.

Java component PDF library for integrating with the ComPDF API to create a PDF viewer and editor.