How to Add Files to Zip in C#

In the ever-evolving landscape of software development, the efficient manipulation of zip files is a fundamental aspect. The ability to create a zip adds a dynamic dimension, as C# add files to zip archives. This enhances the versatility and compressibility of bundled data for streamlined storage and transmission, showcasing the power of C# in optimizing file management.

Understanding the Need: The Evolution of Zip Archives

As projects progress, the need to modify existing zip archives becomes evident. This step could stem from various scenarios, such as adding new files, output zip archives, updates to existing ones, or the dynamic generation of content. Augmenting an existing zip archive without recreating it is a crucial functionality for developers. This process not only saves valuable time but also ensures efficient resource utilization.

In this article, we will explore how to add files and folders to an existing zip archive in C# using the feature-rich capabilities of the IronZip library.

IronZip - A C# ZIP Archive Library

IronZIP is a powerful C# ZIP archive library designed to simplify the complexities of managing zip archives. It is a robust and versatile C# ZIP archive library designed to streamline the creation, reading, and extraction of archives in .NET applications. Renowned for its user-friendly API, IronZip prioritizes accuracy, ease of use, and speed.

Key Features of IronZip

Cross-Platform Support:

IronZip exhibits remarkable compatibility, functioning seamlessly across a diverse range of platforms. Whether you're operating on Windows, Linux, Mac, iOS, Android, Docker, Azure, or AWS, IronZip has you covered.

.NET Compatibility:

One of IronZip's strengths is its comprehensive support for various .NET versions, including 7, 6, Core, Standard, and Framework.

File Format Support:

IronZip is not confined to handling just ZIP archives; it extends its capabilities to TAR, GZIP, and BZIP2 archives, providing a versatile solution for diverse file formats.

Versatility in Language and Project Types:

Designed flexibly, IronZip supports multiple programming languages, including C#, F#, and VB.NET. It seamlessly integrates into various project types, spanning web, mobile, desktop, and console applications.

User-Friendly API:

IronZip's API focuses on user-friendliness, ensuring developers can swiftly and intuitively incorporate archive management functionalities into their .NET projects.

Integration with Popular IDEs:

Developers can leverage the power of IronZip within familiar environments. The library integrates with widely-used IDEs such as Microsoft Visual Studio and JetBrains ReSharper & Rider.


It's essential to have the necessary prerequisites before adding files to an existing zip archive using this.

  1. Visual Studio Installation:

    • Ensure that Visual Studio, the comprehensive, integrated development environment for C# applications, is installed. If not, download it from the official website.
  2. Create a console Application:

    • Open Visual Studio and Create a New Project.
    • Configure Project name and location.
    • Choose the suitable .NET Framework. IronZip supports the latest .NET technologies to work with.


  3. IronZip Package Integration:

    • Utilize the NuGet Package Manager Console from the Visual Studio Tools menu to integrate the IronZip library into your project seamlessly. Execute the following command in the Package Manager Console:
    Install-Package IronZip
    Install-Package IronZip
    'INSTANT VB TODO TASK: The following line uses invalid syntax:
    'Install-Package IronZip
    VB   C#
    • Or you can open Manage NuGet Package Manager for Solutions from Solution Explorer. Then, in the NuGet tab, browse for IronZip to install.


Steps to Add Files to an Existing Zip File

Now, let's dive deep into the implementation of adding files to a zip file from an existing zip archive in C# using IronZip.

Step 1: Import the IronZip Namespace

using IronZip;
using IronZip;
Imports IronZip
VB   C#

To access the functionalities provided by IronZIP, ensure you include the IronZip namespace at the beginning of your C# file to create zip files, read and extract from zip files and modify them seemlessly.

Step 2: Open and Modify the Existing Zip Archive

The core of adding files to an existing zip archive lies in opening and modifying the file archive using a system call. The following code sample demonstrates this process:

using (var archive = IronArchive.FromFile("", "", 9))
    // Add new files to the existing archive
using (var archive = IronArchive.FromFile("", "", 9))
    // Add new files to the existing archive
Using archive = IronArchive.FromFile("", "", 9)
	' Add new files to the existing archive
End Using
VB   C#

Code Explanation

  • FromFile Method: This method is employed to open an existing zip archive specified by the "" string filename. Simultaneously, a new archive named "" is created, representing the var file, in the specified directory, where the modifications will be applied.
  • Compression Level: The FromFile method also provides a compression level to compress files and create a minimum-size zip file system. The third argument, 9, denotes the compression level, indicating the extent of compression applied to the individual files contained within the archive. The default is 9 with the highest compression rate and 0 with the weakest.
  • AddArchiveEntry: This method facilitates the addition of new files to the existing archive. This will add all the files to the current zip file.

Step 3: Execution of the Program

Build and run your application to execute the code. The specified files will seamlessly integrate into the existing zip archive.

Step 4: Verification of Result Output Zip archive

Navigate to the project directory and inspect the path to the modified zip archive (""). It should now encompass both the original files and the newly added ones, showcasing the success of the augmentation process.

csharp-add-files-to-zip-tutorial-3The simplicity and efficiency exhibited by IronZip empower developers to handle complex tasks with ease. This capability becomes invaluable in real-world applications when adapting to changing project requirements or incorporating dynamically generated content into existing archives.


In conclusion, IronZip is a robust and versatile solution for handling zip archives in C#. Its comprehensive feature set, cross-platform compatibility, and seamless integration into various .NET projects make it an indispensable tool for developers. Following the outlined steps, developers can dynamically modify existing zip archives, enriching their applications with efficient file management and compression capabilities.

With IronZIP, adding files to existing zip archives becomes a smooth and intuitive experience. As projects evolve and demand flexibility, IronZip stands ready to meet the challenges, empowering developers to manage their file archives confidently and efficiently. For further details and to harness the full potential of IronZIP, refer to the official IronZip documentation.


While IronZip provides a robust solution for zip archive and folder management, it's essential to be aware of its licensing model. Like other products from Iron Software, IronZip typically adheres to a commercial licensing model. This implies that for usage in commercial projects, acquiring a license may be necessary. For detailed information on licensing options and pricing, refer to the official IronZip license page.

Iron Software generously offers a free trial version for those inclined to explore IronZip before making a financial commitment. This trial period allows developers to assess the library's features, functionality, and compatibility with their projects before deciding on a full license. To initiate the exploration, visit the IronZip download page.