Self-hosted document viewing for .NET

.NET Document Viewer SDK for PDF, Office and CAD

Embed secure document viewing in C# and .NET applications, including ASP.NET Core, Blazor, MVC, Razor Pages, and JavaScript frontends. Render PDF, Office, CAD, email, and images on Windows or Docker without Microsoft Office.

Try the viewerExplore all 76 formats
Doconut Viewer displaying a presentation deck with page thumbnails and document controls
Broad format coverage
76

Replace separate Office, PDF, CAD, email, and image viewers with one API.

Format-aware rendering
19

Each family uses controls designed for its document structure and workflow.

Precision controls
25 to 300 DPI

Balance sharp output and processing cost for each application and document.

Private processing
Your infrastructure

Render server-side without sending source documents to a third-party viewer service.

The viewing experience

Everything users expect from a document viewer

Keep users inside your application with familiar navigation and inspection tools instead of sending them to a download or a separate desktop program.

Doconut Viewer page thumbnails and document navigation
A document page rotated in Doconut Viewer with thumbnails visible

Navigate long documents

Use page thumbnails, direct page selection, previous and next controls, continuous scroll, and drag-to-pan navigation.

thumbnails · page jump · previous / next · pan

Inspect every detail

Zoom in or out with configurable steps and limits, then fit content by width, height, or page.

PageZoom · ZoomStep · MaxZoom · FitType

Correct page orientation

Rotate pages in 90-degree steps or flip them horizontally and vertically without changing the source file.

Rotate · Flip · per-page transform state

Complete the viewing task

Expose print, export, full-screen, upload, and sample-file actions in the host toolbar around the embedded viewer.

print · export · full screen · host callbacks

Stay responsive on large files

Lazy page loading, thumbnail previews, page-level memory caching, optional browser caching, and a large-document strategy reduce unnecessary work.

LargeDoc · CachePages · CacheEnabled · lazy load

Format coverage

76 extensions across 19 format families

The list below is generated from the same shipping catalog the SDK uses to decide whether a file is viewable. It includes every verified extension and the controls available for its family.

Open the complete format matrix

Business documents

PDF

1 extension

Resolution, passwords, link extraction, search and copy flags, image compression, resizing, and segmented rendering.

.pdf

Word and OpenDocument text

10 extensions

Resolution, culture, passwords, paper size, margins, page color, encoding, font folders, and table autofit.

.doc .docx .docm .dot .dotx .dotm .rtf .odt .ott .xml

Excel, OpenDocument sheets, and CSV

8 extensions

Resolution, page setup, autofit, formula calculation, sheet selection, print area, gridlines, and worksheet splitting.

.xls .xlsx .xlsm .xlsb .xltx .xltm .ods .csv

PowerPoint and OpenDocument presentations

9 extensions

Resolution, passwords, font folders, fast loading, and direct or PDF-backed rendering.

.ppt .pptx .pptm .ppsx .ppsm .pot .potx .potm .odp

Technical and planning files

AutoCAD drawings

2 extensions

Resolution, color, background, line width, model and layouts, 3D solids, output bounds, scaling, and render quality.

.dwg .dxf

DGN drawings

1 extension

Resolution, model and layout visibility, automatic scaling, background, line width, and image or text quality.

.dgn

Microsoft Visio

9 extensions

Resolution, direct or PDF-backed rendering, page caching, and PDF/A export configuration.

.vsd .vsdx .vss .vssx .vst .vstx .vdx .vsx .vsdm

Microsoft Project

2 extensions

Resolution, paper size, day or month time scale, and five views including Gantt, task, and resource layouts.

.mpp .mpx

Images and medical imaging

Raster, vector, camera, and design images

18 extensions

Resolution, a configurable maximum output size, transparent PNG handling, page caching, and UI visibility.

.jpg .jpeg .jpe .png .bmp .gif .ico .eps .tga .webp .cdr .cmx .dng .emf .wmf .avif .svg .jp2

Multi-page TIFF

2 extensions

Multi-page viewing with configurable resolution, page caching, and the shared viewer UI controls.

.tif .tiff

Adobe Photoshop

1 extension

Resolution plus a configurable maximum output size for large layered design files.

.psd

Doconut DICOM

2 extensions

Horizontal and vertical DPI, frame delay, loop count, and animation-only, frames-only, or combined display through the DICOM plugin.

.dcm .ima

Email, web, text, and interchange

Email messages

3 extensions

Resolution, message encodings, external-image policy, time zone, page sizing, antialiasing, and high-quality rendering.

.eml .emlx .msg

EPUB

1 extension

Resolution, direct or PDF-backed rendering, page caching, password, culture, and UI controls.

.epub

XPS

1 extension

Resolution and PDF-backed rendering with configurable PDF behavior, caching, and viewer UI.

.xps

HTML

2 extensions

Resolution and direct or PDF-backed rendering with shared password, culture, caching, and UI controls.

.html .htm

MHT and MHTML

2 extensions

Resolution and PDF-backed rendering for a reliable page projection, with cache and viewer UI controls.

.mht .mhtml

Plain text

1 extension

Resolution, paper size, file encoding, font selection, culture, page caching, and UI controls.

.txt

Doconut native format

1 extension

Native Doconut viewing with configurable resolution, page cache, culture, and viewer UI.

.dcn

DICOM viewing requires the Doconut DICOM plugin. DCN is Doconut's native document format. The exact extension count excludes converter-only formats.

Optional workflows

Extend the Viewer without replacing it

Add focused capabilities around the same embedded experience when a project needs review, discovery, conversion, or medical imaging.

Doconut Annotation Plugin icon

Annotation

Add comments, highlights, shapes, stamps, signatures, and collaborative review tools to documents.

Explore Annotation
Doconut Search Plugin icon

Search

Find words and phrases with result previews, highlighting, and navigation back through previous results.

Explore Search
Doconut Converter Plugin icon

Converter

Convert major document formats on your server through one private and consistent API.

Explore Converter
DICOM medical imaging frames rendered by Doconut

DICOM

Open DCM and IMA medical imaging files with configurable multi-frame animation and frame-by-frame viewing.

Explore DICOM

Private by architecture

Keep document processing inside your infrastructure

Doconut renders server-side and gives your application control over sessions, storage, delivery, caching, and distributed processing.

Deployment options

Windows and Docker

Run directly on Windows or package your application in Docker while keeping processing under your control.

Server-side control

Open a path or stream inside ASP.NET, return an opaque session token, and serve page images without sending source documents to an external viewer service.

  • Request-origin validation enabled by default
  • Configurable sliding session expiration
  • Password-protected document support
  • Explicit session close and resource cleanup

Cloud and storage adapters

Route document artifacts through the storage already approved by your organization instead of coupling the viewer to one cloud vendor.

  • Microsoft Azure Blob Storage
  • Amazon S3
  • Google Cloud Storage
  • Redis and file shares
  • Dropbox and FTP or FTPS
  • CDN-backed delivery

Native distributed workflows

The new .NET 8 architecture, also brought to the updated .NET 6 edition, supports shared artifacts and rendering workflows for scaled-out applications.

  • Shared file-store publishing
  • Background-render readiness and retry
  • First-page-priority support
  • Artifact retention and cleanup
  • Per-document function configuration
  • Cache and health-check integration

Format-aware rendering

Tune output for the document, not just the viewer

A shared configuration controls common behavior, while format-specific classes expose the settings that matter for spreadsheets, drawings, messages, images, presentations, and medical frames.

ImageResolution accepts 25 to 300 DPI. Office, PDF, CAD, TIFF, email, web, and text families default to 200 DPI; image, PSD, and DICOM families default to 100 DPI.

Shared controls

Set resolution, culture, password, UI visibility, and in-memory page caching across format-specific configurations.

ImageResolution · DocumentCulture · Password · ShowUI · CachePages

Office and PDF

Control fonts and page setup in Word and PowerPoint, worksheet calculation and print behavior in Excel, and links or image optimization in PDF.

FontFolders · PaperSize · SplitWorksheets · PrintArea · ExtractHyperlinks · CompressImages

CAD, Project, and images

Choose CAD layouts and quality, Project presentation views and time scale, or image output bounds and PNG transparency.

ShowLayouts · ShowModel · QualityText · PresentationFormat · MaxImagePixelSize · TransparentPng

Email and DICOM

Control message encodings, external-image policy and time zone, plus medical frame resolution, playback timing, looping, and display mode.

EmailEncoding · SkipExternalImages · TimeZoneOffset · HorizontalResolution · AnimationFrameDelayMs · DisplayMode

Technical fit

Four .NET targets, one Viewer product

Choose the package that matches your application. We recommend Doconut .NET 8 for new projects and upgrades, while preserving clear paths for existing applications.

Recommended for new development and upgrades

Doconut .NET 8

Our native modern edition combines dependency injection, async APIs, embedded resources, security middleware, and distributed deployment support.

  • Windows and Docker deployment
  • ASP.NET Core, MVC, Razor Pages, and Blazor
  • Distributed storage and caching options
Explore .NET 8

Doconut .NET 6

Recommended update for net6.0 applications

Upgrade from the legacy .NET 6 package to the new DI, middleware, async, security, and distributed architecture while your application remains on net6.0.

View the new .NET 6

.NET Standard / Core

Continue an established ASP.NET Core integration based on the classic Doconut middleware and Viewer workflow.

View setup

.NET Framework

Support mature ASP.NET applications that use the DocImage handler and traditional Doconut configuration.

View setup

Plan the integration or upgrade with confidence

Use the documentation for setup and migration details. If a question remains, ask the Doconut support community in the forum.

View documentationVisit support forum

Move from evaluation to integration

Register Doconut through dependency injection, serve its embedded resources, and open documents asynchronously from your application.

Doconut Viewer embedded in a web application

Viewer licensing

Choose the Doconut Viewer license that matches your development team, deployment, and distribution model.

Developer

$599

For one developer deploying the Viewer on one domain and its subdomains.

Updates and product support included

Buy Viewer

Site

$1799

For organizations running the Viewer across multiple internal or customer-facing domains.

Updates and product support included

Buy Viewer

SDK

$2999

For vendors embedding Doconut in commercial software intended for redistribution.

Updates and product support included

Buy Viewer

Evaluate the Viewer with your real documents

Test the complete viewing workflow, validate the formats and deployment your project needs, then choose the right .NET package.

Download free trialContact sales