Document Annotation REST API for Your Apps & Websites

RESTful API that allows you to add cross-platform compatible, multi-format document & image annotation functionality to your web-based app or website

  Start Free Trial
Document Annotation REST API

GroupDocs.Annotation for Cloud


GroupDocs.Annotation for Cloud is a universal document annotator that supports almost all common business document and image file formats, including PDF, Microsoft Word, Excel, PowerPoint, Visio, Project, CAD, TIFF, JPG and many more. API also works with all popular third-party cloud storage providers, including Amazon S3, Windows Azure, Box, Google Cloud and Dropbox. You can also easily integrate GroupDocs.Annotation into your CMS using our plugins.

Advanced Document Annotation REST API Features



Multiple file formats support


Cross-platform compatibility


Unmatched online annotation UX


Flexible deployment options


Easy integration


Guarantee the security of documents


Robust set of annotation tools


Real-time annotation


3rd Party Integrations

Cross-Platform Compatibility

GroupDocs.Annotation works perfectly across platforms. Documents can be annotated from desktop, tablet or mobile devices using any modern web-browser, including Internet Explorer 8+, FireFox, Chrome, Safari 5+, Opera and their mobile versions.

Supported Browsers
  • IE8+
  • Chrome
  • Chrome for Android
  • Firefox
  • Firefox for Android
  • Opera
  • Opera Mini
  • Opera for Android
  • Safari 5+
  • Mobile Safari
Supported Devices
  • iPhone
  • iPad
  • Android
  • PC
  • Mac

Real-Time Annotation

The same document can be annotated by several users at a time, allowing reviewers to see and reply to each other’s notes. And with the presentation mode enabled, mouse, scroll and zoom events can be broadcast in real-time.

Guarantee the security of documents

To guarantee the security of your documents, GroupDocs SaaS servers are hosted using the industry-leading Amazon EC2 infrastructure. All document processing operations and API calls are made through SSL. For more details on security of the Amazon EC2 infrastructure, please see this page.

In case you prefer to store and host documents on your own servers, please consider our downloadable GroupDocs.Annotation for .NET or Java APIs.

Convenient Web UI

GroupDocs.Annotation comes with a web-based UI that can be easily customized with your own CSS and embedded to your app or website using a simple iframe or few lines of a JavaScript code. The UI is designed to help users seamlessly view, navigate and collaborate on documents from a browser. It allows users to:

  • Scroll and turn document pages like slides.
  • Preview and navigate pages with thumbnails.
  • Jump straight to a specified page within the document.
  • Search for text within the document using keywords.
  • Zoom in/out of a document or fit to width or height.
  • See a list of all added comments and markup.
  • Jump between comments and markup within the document.
  • Invite reviewers via email and manage their access rights.
  • Share, download and print documents with added notes.
  • Export annotated documents to PDF.

Robust Set of Annotation Tools

  • Area annotation – add notes to an area highlighted with a rectangle.
  • Point annotation – add notes to any point in the document.
  • Typewriter – add sticky notes with rich text.
  • Text annotation – add comments to selected text.
  • Strikeout/underline – highlight text with strikethroughs/underlines.
  • Text replacement – highlight which text should be replaced with what.
  • Text redaction – hide confidential text.
  • Area redaction – hide confidential parts of an image or text.
  • Polyline – draw freehand lines and shapes.
  • Pointer/arrow – drop arrows pointing to an object.
  • Watermark – create text-based watermark overlays.
  • Ruler – measure the distance between any objects in a document.
  • Undo/redo – cancel or reverse annotations placed on a document.

Flexible Deployment Options

GroupDocs.Annotation for Cloud API is delivered using a SaaS model and is hosted on secure Amazon EC2 servers. In case you need to keep your documents in-house, please also consider our .NET and Java APIs for on-premises deployment.

Easy Integration

It is easy to integrate GroupDocs.Annotation for Cloud into your app or website, as there is nothing to install on the server- or client-side. Documents, along with the annotation UI, can be embedded using a simple iFrame. We also offer SDKs to help you set it up quickly.

Support and Learning Resources


GroupDocs.Annotation offers document automation APIs for other popular development environments as listed below: