# Adding Attachments to Adobe PDF Documents using C# > TX Text Control is used to create electronic document containers by embedding files in Adobe PDF documents. This tutorial shows how to add and extract attachments to and from PDF documents. - **Author:** Bjoern Meyer - **Published:** 2022-02-25 - **Modified:** 2025-11-16 - **Description:** TX Text Control is used to create electronic document containers by embedding files in Adobe PDF documents. This tutorial shows how to add and extract attachments to and from PDF documents. - **3 min read** (471 words) - **Tags:** - Angular - ASP.NET - ASP.NET Core - Digital Documents - PDF - **Web URL:** https://www.textcontrol.com/blog/2022/02/25/adding-attachments-to-adobe-pdf-documents-using-csharp/ - **LLMs URL:** https://www.textcontrol.com/blog/2022/02/25/adding-attachments-to-adobe-pdf-documents-using-csharp/llms.txt - **LLMs-Full URL:** https://www.textcontrol.com/blog/2022/02/25/adding-attachments-to-adobe-pdf-documents-using-csharp/llms-full.txt --- PDF/A-3 allows the embedding of any file type into PDF documents. That allows the progression from electronic paper to an electronic container that holds the human and machine-readable versions of a document. Applications can extract the machine-readable portion of the PDF document in order to process it. A PDF/A-3 document can contain an unlimited number of embedded documents for different processes. > **Learn more** > > PDF/A-3 permits the embedding of files of any format. This article gives an overview of the advantages of PDF/A-3 as an electronic container. > > [PDF/A-3: The Better Container for Electronic Documents](https://www.textcontrol.com/blog/2020/07/23/pdfa-the-better-container-for-electronic-documents/llms-full.txt) In this article you will learn how to embed a plain text file into a PDF document and how to extract the attachment from the PDF document. ### Adding Attachments This following sample code shows how TX Text Control can be used to attach the text file to a PDF document: ``` // create a non-UI ServerTextControl instance using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl()) { tx.Create(); // set dummy content tx.Text = "PDF Document Content"; // read the content of the attachment string sAttachment = System.IO.File.ReadAllText("attachment.txt"); // create the attachement TXTextControl.EmbeddedFile attachment = new TXTextControl.EmbeddedFile( "attachment.txt", sAttachment, null) { Description = "My Text File", Relationship = "Unspecified", MIMEType = "application/txt", CreationDate = DateTime.Now, }; // attached the embedded file tx.DocumentSettings.EmbeddedFiles = new TXTextControl.EmbeddedFile[] { attachment }; // save as PDF/A tx.Save("document.pdf", TXTextControl.StreamType.AdobePDFA); } ``` The EmbeddedFile object represents the attachment. In the constructor, the file name, the data and additional meta data can be added. Additionally, the MIME type of the attachment (*application/text* in our case), a textual description, a relationship and the creation date is provided. The relationship is an optional string describing the relationship of the embedded file and the containing document. It can be a predefined value or should follow the rules for second-class names (ISO 32000-1, Annex E). Predefined values are **"Source"**, **"Data"**, **"Alternative"**, **"Supplement"** or **"Unspecified"**. When opening the document in Adobe Acrobat Reader, you will find the attachment in the *Attachments* side-panel. ![PDF Attachments](https://s1-www.textcontrol.com/assets/dist/blog/2022/02/25/a/assets/attachment.webp "PDF Attachments") ### Extracting Attachments The following code is loading the created PDF file in order to find the attachment by looping through all embedded files. The found attachment is then extracted and exported as a text file. ``` // create a non-UI ServerTextControl instance using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl()) { tx.Create(); // load the PDF document TXTextControl.LoadSettings ls = new TXTextControl.LoadSettings(); tx.Load("document.pdf", TXTextControl.StreamType.AdobePDF, ls); // read the attachments TXTextControl.EmbeddedFile[] files = ls.EmbeddedFiles; // find the specific attachment and save it foreach(TXTextControl.EmbeddedFile file in files) { if (file.Description == "My Text File") { string sAttachment = Encoding.UTF8.GetString((byte[])file.Data); System.IO.File.WriteAllText("attachment_read.txt", sAttachment); break; } } } ``` --- ## About Bjoern Meyer As CEO, Bjoern is the visionary behind our strategic direction and business development, bridging the gap between our customers and engineering teams. His deep passion for coding and web technologies drives the creation of innovative products. If you're at a tech conference, be sure to stop by our booth - you'll most likely meet Bjoern in person. With an advanced graduate degree (Dipl. Inf.) in Computer Science, specializing in AI, from the University of Bremen, Bjoern brings significant expertise to his role. In his spare time, Bjoern enjoys running, paragliding, mountain biking, and playing the piano. - [LinkedIn](https://www.linkedin.com/in/bjoernmeyer/) - [X](https://x.com/txbjoern) - [GitHub](https://github.com/bjoerntx) --- ## Related Posts - [Creating Advanced Tables in PDF and DOCX Documents with C#](https://www.textcontrol.com/blog/2024/09/30/creating-advanced-tables-in-pdf-and-docx-documents-with-csharp/llms.txt) - [How to Choose the Best C# Library for your Document Processing Needs](https://www.textcontrol.com/blog/2023/08/07/how-to-choose-the-best-library-for-your-document-processing-needs/llms.txt) - [Using QR Codes in PDF Documents in C# .NET](https://www.textcontrol.com/blog/2026/04/21/using-qr-codes-in-pdf-documents-in-csharp-dotnet/llms.txt) - [Why Structured E-Invoices Still Need Tamper Protection using C# and .NET](https://www.textcontrol.com/blog/2026/03/24/why-structured-e-invoices-still-need-tamper-protection-using-csharp-and-dotnet/llms.txt) - [Create Fillable PDFs from HTML Forms in C# ASP.NET Core Using a WYSIWYG Template](https://www.textcontrol.com/blog/2026/03/17/create-fillable-pdfs-from-html-forms-in-csharp-aspnet-core-using-a-wysiwyg-template/llms.txt) - 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