OST Viewer REST API, SDK & App for .NET | GroupDocs Viewer Cloud

GroupDocs.Viewer Cloud provides .NET developers with a robust suite of APIs to integrate advanced document viewing functionalities into their applications. Our free OST Viewer REST API and SDK allow users to effortlessly view OST images directly within their apps, eliminating the need for additional downloads or installations. Beyond OST, our APIs support a wide range of formats, including Microsoft Office, AutoCAD, and more, ensuring versatility and broad compatibility for diverse application requirements.

In addition to our powerful APIs, GroupDocs.Viewer Cloud offers a free online OST Viewer App that enables users to view and annotate OST files directly from their browsers. This app requires no installation, making it perfect for quick document access and collaboration. Users can highlight text, add annotations, and share documents via email, streamlining workflows and enhancing productivity. Whether used independently or integrated into your application, our online app provides a flexible and efficient solution for document interaction.

Moreover, GroupDocs.Viewer Cloud supports multiple platforms beyond .NET. Python developers can take advantage of our comprehensive SDKs, complete with clear documentation and practical examples, to add OST viewing capabilities to their projects seamlessly. The API Explorer feature allows developers to test and explore API functionalities directly in their browsers, offering an interactive way to understand and implement our solutions effectively.


  • View OST Online via Node.js or Free Online App
  • View OST Online via Python or Free Online App
  • View OST Online via PHP or Free Online App
  • View OST Online via Ruby or Free Online App
  • View OST Online via Java or Free Online App
  • View OST Online via cURL or Free Online App
  • View OST Online via Android or Free Online App

.NET OST Viewer REST APIs & SDK

View OST and other Popular Formats for Free

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How to view OST file online

  • Select the file by clicking the OST App or simply drag & drop a OST file.
  • Click the Open button to upload and view OST file.
  • That is all! You can view your OST document online.

Frequently Asked Questions

How secure is the document viewing process in GroupDocs.Viewer Cloud?

GroupDocs.Viewer Cloud ensures a secure document viewing process with data encryption, secure protocols, and adherence to data protection standards.

Is there a limit on the number of document views I can generate using GroupDocs.Viewer Cloud APIs?

GroupDocs.Viewer Cloud APIs offer flexible limits on the number of document views based on your subscription plan. Contact GroupDocs support for more details on view limits.

What are the benefits of using GroupDocs.Viewer Cloud Free Apps?

GroupDocs.Viewer Cloud Free Apps provide a convenient way to explore and test the document viewing capabilities before subscribing to a paid plan.

Does GroupDocs provide technical support for issues related to GroupDocs.Viewer Cloud Free Apps?

GroupDocs offers technical support for Free Apps users to assist with any technical difficulties or inquiries related to the GroupDocs.Viewer Cloud platform.

Can I try OST online viewer for free?

GroupDocs.Viewer Cloud App is completely free. You can view as many OST and other files as you may like. If you are a developer and want to add this feature in your own app, you can try GroupDocs.Viewer Low-Code APIs without any limitations.

What features does GroupDocs.Viewer Cloud offer?

GroupDocs.Viewer Cloud provides various features, such as zooming, paging, searching within documents, text selection, and rendering options. You can render specific pages, generate document thumbnails, or even render documents as images.

How can I access GroupDocs.Viewer Cloud Free Apps?

GroupDocs.Viewer Cloud Free Apps can be accessed directly from the GroupDocs website or through the GroupDocs web or mobile applications.

What document formats does GroupDocs.Viewer Cloud support?

GroupDocs.Viewer Cloud supports a wide range of document formats, including PDF, Microsoft Word (DOC, DOCX), Excel (XLS, XLSX), PowerPoint (PPT, PPTX), images (JPEG, PNG, GIF, TIFF), and more.

How can I integrate GroupDocs.Viewer Cloud into my application?

Integration is done through APIs provided by GroupDocs.Viewer Cloud. The service offers APIs for different programming languages and platforms, making it convenient for developers to incorporate document viewing capabilities into their applications or websites.

Are there any limitations to the features available in GroupDocs.Viewer Cloud Free Apps?

GroupDocs.Viewer Cloud Free Apps may have restrictions on the number of document views, file types supported, or advanced functionalities compared to paid plans.

Are there SDKs available for GroupDocs.Viewer Cloud APIs?

Yes, GroupDocs provides SDKs for various programming languages to simplify the integration and utilization of Viewer Cloud APIs in your applications.

I do not want to upload my confidential OST files anywhere? What are my options?

GroupDocs.Viewer Cloud is also available as Docker image which can be used to self-host the service. Or you may build your own services using GroupDocs.Viewer High-code APIs which currently drive both OST Free Viewer App and REST APIs.

Are there any limitations or usage restrictions with GroupDocs.Viewer Cloud?

GroupDocs.Viewer Cloud has certain usage limits depending on the subscription plan you choose. These limits may include the number of API requests, document size, or the number of concurrent connections. Its recommended to review the pricing and plans to understand the specific limitations.

What file formats are supported by GroupDocs.Viewer Cloud APIs?

GroupDocs.Viewer Cloud APIs support a wide range of file formats including PDF, Word, Excel, and more.

I want to create my own app that can view OST file online?

Check our Cloud SDKs at GitHub if you are looking for the source code to view OST file format in the Cloud.

Can GroupDocs.Viewer Cloud Free Apps be used for commercial purposes?

GroupDocs.Viewer Cloud Free Apps are primarily for evaluation and testing purposes. For commercial use, consider upgrading to a paid subscription plan for full functionality and support.

How reliable is the performance of GroupDocs.Viewer Cloud Free Apps?

GroupDocs.Viewer Cloud Free Apps offer reliable performance and high-quality document viewing experience, ensuring smooth and seamless viewing of various file formats.

Outlook Offline Data File (OST) Viewer REST API

View OST as Images like BMP, PNG, JPEG & TIFF

Get OST document information like page & attachment count as well as properties

Rotate, reorder & watermark OST pages

View OST as PDF

View OST as HTML5

OST REST APIs are secured and require authentication

View OST and hundreds of other formats from CAD, Word, PowerPoint, Excel, Email & eBook

View OST with its attachments

Free Apps availability

Users can access and utilize FREE Apps for document viewing and annotation online, providing a convenient and cost-effective solution for accessing and interacting with document content.

Free Alternative to Desktop & Mobile OST Viewer Apps

GroupDocs.Viewer Cloud app does not need any installation or setup to view OST. You can quickly start using the Viewer App in your browser to view any number of files per day absolutely free of charge.

Self-host OST Cloud Viewer Free App

The GroupDocs.Viewer Cloud Container Image enables users to self-host GroupDocs.Viewer Cloud for OST using Docker.

Flexible Rendering of OST Documents

GroupDocs.Viewer is a powerful document viewer REST API that allows you to display over 186 document formats in your applications. It allows rendering of OST for the whole document, page by page or custom range of pages.

Show or hide document headers and footers

GroupDocs.Viewer Cloud APIs supports rendering of headers and footers.

Integration capabilities

Developers can easily integrate the Viewer Cloud APIs into their applications to enable users to view documents directly within the application interface without the need to download them.

Free Apps support show or hide document comments

API Allows to view and comments embedded inside supported documents types.

Wide range of document format support

GroupDocs.Viewer Cloud APIs and FREE Apps support a variety of document formats including PDF, Microsoft Office (Word, Excel, PowerPoint), AutoCAD, image files (PNG, JPEG), and more.

Free online OST viewer supports over 186 file formats

The cloud-based viewer API for OST has the ability to display different document formats quickly, with just a few lines of code. Using the SDK for .NET you can find out about the various document formats supported by the SDK.

Zooming functionality

The Viewer Cloud APIs provide zooming capabilities, allowing users to zoom in and out of document pages to view content in more detail or from a broader perspective.

GroupDocs.Viewer Cloud REST API Explorer

The easiest way to try out GroupDocs.Conversion Cloud API right away in your browser is by using GroupDocs Cloud Web API explorer, which is a collection of Swagger documentation for the GroupDocs Cloud APIs.It allows you to effortlessly interact and try out every single operation our APIs exposes.

Online document viewing

Users can view documents online without the hassle of downloading them first, providing a convenient and efficient way to access and interact with document content.

Text selection

Users can select, copy, and paste text directly from documents, making it easy to extract and use information from the content.

Extract document text while rendering in image mode

Our API allows extract text from documents

Programmatically get list of supported file types.

Use our REST API to get list of 186 supported document types.

Minify OST Output Content

One of the most exciting features of our Cloud-based viewer API for OST is its ability to minify the output content. Minification removes comments, extra white-spaces, and other unneeded characters without breaking the content structure. As a result, the page becomes smaller in size and loads faster.

Render OST files to remote FTP or Cloud storage

Use third-party cloud storage to save your OST rendered files.

  • Amazon S3
  • Azure Storage
  • Google Cloud Storage
  • Google Drive
  • Dropbox
  • Box
  • FTP

Printing support

Users can print documents directly from the viewer, enabling them to easily generate physical copies of the document content if needed.

Page navigation

The APIs offer intuitive page navigation features that allow users to navigate through document pages easily and efficiently.

Support and Learning Resources

Learning Resources

Product Support

Start Free Trial
Download GitHub Repository

View OST using SDKs in other popular languages

View OST Online via Node.js or Free Online App GroupDocs.Viewer
Cloud SDK for Node.js

View OST Online via Python or Free Online App GroupDocs.Viewer
Cloud SDK for Python

View OST Online via PHP or Free Online App GroupDocs.Viewer
Cloud SDK for PHP

View OST Online via Ruby or Free Online App GroupDocs.Viewer
Cloud SDK for Ruby

View OST Online via Java or Free Online App GroupDocs.Viewer
Cloud SDK for Java

View OST Online via cURL or Free Online App GroupDocs.Viewer
Cloud for cURL

View OST Online via Android or Free Online App GroupDocs.Viewer
Cloud SDK for Android

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