ConcatPDF is the tool to concatenate PDF files. It can concatenate, extract, encrypt, decrypt, configure PDF files, convert image files to PDF. GUI version and CUI version are both available.
iText.NET is iText porting on .NET Framework by J#. This library allows you to generate PDF, (X)HTML, XML, RTF files on Microsoft.NET Framework including ASP.NET.
iText is an open-source PDF library available for Java and .NET (C#). iText allows you to effortlessly generate and manipulate standards-compliant PDF documents with a powerful and feature-rich SDK.
With iText, you can create archivable and accessible PDFs, split and merge documents, fill and flatten forms, digitally sign documents, and more. iText add-ons enable additional functionality, such as PDF creation from HTML templates, secure redaction, OCR, and much more.
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PDF Clown is a general-purpose Java and .NET library for manipulating PDF files through multiple abstraction layers, rigorously adhering to PDF 1.7 specification (ISO 32000-1).
This project aims to provide a universal access to PDF files (creation, reading, editing, rendering...) through an accurate and elegant object-oriented API.