GroupDocs.Viewer 26.8.0

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GroupDocs.Viewer for .NET is a document rendering API that displays 190+ file formats as HTML, PDF, PNG, and JPEG — without installing Microsoft Office, OpenOffice, or any other third-party software. Use it to build document viewers for web, desktop, and mobile applications in C#, F#, or VB.NET.

Get Started

dotnet add package GroupDocs.Viewer

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;

using (var viewer = new Viewer("resume.docx"))
{
    // One HTML file per page; {0} is replaced with the page number.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    viewer.View(viewOptions);
}

How It Works

GroupDocs.Viewer is a metapackage. Restoring it brings in the runtime package that matches your target framework, so you reference one package name whatever you build for:

Rendering is self-contained: the engine is bundled in the package, so no office suite, printer driver, or other external software has to be installed on the machine.

Features

• Render to HTML, PDF, PNG, and JPEG through a single unified API.
• HTML with embedded or external resources — one self-contained file per page, or markup plus separate CSS, fonts, and images.
• Page control: render a single page, a range, or reorder and rotate pages.
• Document information: page count, file format, and page dimensions before rendering.
• Password-protected documents: open and render encrypted files.
• Flexible input: load from a file path or a stream.
• Text watermarks on rendered output.
• Font handling: supply custom font directories and control substitution.
• Output tuning: image quality, resource minification, and text-as-image options.
• ASP.NET Core UI via the GroupDocs.Viewer.UI package.

See the Features overview for details.

Common Tasks

• Display documents in a browser with no Office install and no browser plugin
• Convert an uploaded file to PDF for download or archiving
• Generate page thumbnails and previews for a document library
• Read page count and format before deciding how to process a file
• Watermark previews for preview-only or DRM-style workflows
• Render only the page a user is viewing, for fast paging through large documents
• Render password-protected documents supplied by users

Supported File Formats

This API renders a broad set of document, image, and data formats, including:

• Word Processing: DOC, DOCX, DOCM, DOT, ODT, RTF, TXT
• Spreadsheets: XLS, XLSX, XLSM, XLSB, ODS, CSV, TSV, Numbers
• Presentations: PPT, PPTX, PPS, PPSX, ODP
• PDF & Fixed Layout: PDF, XPS, OXPS
• Images & Graphics: JPG, PNG, BMP, GIF, TIFF, WEBP, SVG, PSD, AI, CDR
• Metafiles: EMF, WMF
• CAD & 3D: DWG, DXF, DGN, IFC, STL
• Medical Imaging: DICOM
• Email & Outlook: MSG, EML, EMLX, PST, OST, VCF
• Visio Diagrams: VSD, VSDX, VSS, VSX
• Project: MPP, MPT, MPX
• OneNote: ONE
• Web & Markup: HTML, MHTML, XML, JSON
• eBooks: EPUB, MOBI, FB2, CHM, AZW3
• Archives: ZIP, RAR, 7Z, TAR, GZ, BZ2
• Source Code: C#, Java, JavaScript, PHP, Python, SQL, and more

Supports 190+ file formats.

For a complete list, see supported formats.

Examples

Render to HTML

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;

using (var viewer = new Viewer("resume.docx"))
{
    // Embedded resources produce one self-contained HTML file per page.
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    viewer.View(viewOptions);
}

Render to PDF

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;

using (var viewer = new Viewer("solution.pptx"))
{
    var viewOptions = new PdfViewOptions("solution.pdf");
    viewer.View(viewOptions);
}

Render to PNG or JPEG

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;

using (var viewer = new Viewer("flyer.docx"))
{
    var viewOptions = new PngViewOptions("page_{0}.png");
    viewer.View(viewOptions);
}

Render specific pages

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;

using (var viewer = new Viewer("report.docx"))
{
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");

    // Render pages 1 and 3 only.
    viewer.View(viewOptions, 1, 3);
}

Get document information

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;

using (var viewer = new Viewer("invoice.xlsx"))
{
    var info = viewer.GetViewInfo(ViewInfoOptions.ForHtmlView());

    Console.WriteLine("Format: " + info.FileType);
    Console.WriteLine("Pages: " + info.Pages.Count);
}

Load a password-protected document

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;

var loadOptions = new LoadOptions { Password = "123456" };

using (var viewer = new Viewer("encrypted.docx", loadOptions))
{
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    viewer.View(viewOptions);
}

Add a text watermark

using GroupDocs.Viewer;
using GroupDocs.Viewer.Options;

using (var viewer = new Viewer("contract.pdf"))
{
    var viewOptions = new PngViewOptions("page_{0}.png");
    viewOptions.Watermark = new Watermark("CONFIDENTIAL");

    viewer.View(viewOptions);
}

Cache rendering results

Caching makes repeat views of the same document return almost immediately — worth enabling in any web application that renders the same files more than once.

using GroupDocs.Viewer;
using GroupDocs.Viewer.Caching;
using GroupDocs.Viewer.Options;

var cache = new FileCache("cache");
var settings = new ViewerSettings(cache);

using (var viewer = new Viewer("sample.docx", settings))
{
    var viewOptions = HtmlViewOptions.ForEmbeddedResources("page_{0}.html");
    viewer.View(viewOptions);
}

AI Agent & LLM Friendly

• MCP server — connect your AI tool to GroupDocs documentation for on-demand API lookups:

  { "mcpServers": { "groupdocs-docs": { "url": "https://docs.groupdocs.com/mcp" } } }
  

• Machine-readable docs — full documentation as plain text for RAG and LLM context:
  • Single file: https://docs.groupdocs.com/viewer/net/llms-full.txt
  • Per page: append .md to any docs URL

Evaluation Mode

The API works without a license in evaluation mode, with these limitations:

• Only the first 2 pages of a document are rendered.
• A trial watermark is added to the top of each rendered page.

To remove these limitations, apply a license or request a temporary license:

using GroupDocs.Viewer;

var license = new License();
license.SetLicense("GroupDocs.Viewer.lic");

Troubleshooting

System Requirements

• .NET Framework 4.6.2 or later, or .NET 6.0 or later
• Windows (x64/x86/ARM64), Linux (x64/ARM64), macOS (x64/ARM64)
• No Microsoft Office, OpenOffice, or other office suite required

See System requirements for details.

Support

Technical support is available to all users, including those evaluating the product, through the Free Support Forum and the Paid Support Helpdesk.

More Resources

• Documentation
• Code Examples
• Free Support Forum
• Temporary License

Also available for other platforms: Java | Node.js | Python

Product Page | Docs | Demos | API Reference | Examples | Blog | Releases | Free Support | Temporary License