PDF annotation SDK for web applications

Let users highlight, comment, draw, and mark up documents in real time — right in the browser. No downloads, no plugins. Choose from professional annotation tools like sticky notes, arrows, shapes, and text markup, or build custom tools for your specific use case. Control exactly who can view, edit, or delete annotations with granular permissions.

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Main features

Ready-to-use snap-in

Get up and running in minutes with a complete set of annotation tools built in: highlight, sticky notes, shapes, text boxes, freehand drawing — everything you need out of the box.

Customizable

Style annotations to match your brand, or build entirely custom annotation tools for specialized workflows, with full control over appearance and behavior.

XML support

Import and export annotations as standards-compliant XML for seamless integration with other systems and long-term archiving.

Real-time collaboration

Multiple users can annotate the same document simultaneously. Changes appear instantly across all connected sessions — no refresh needed.

Secure workflows

Control who can view, add, edit, or delete annotations with role-based permissions. Add digital signatures, password protection, and redaction for sensitive documents.

Annotate 100+ file formats

Works with PDF, PDF/A, MS Office, SVG, images (TIFF, JPEG, PNG, WEBP), RAW camera formats, and more. Export annotated documents as PDF, PDF/A, TIFF, or SVG.

List of annotations

Each annotation is customizable. Refer to our documentation and our programming tutorials for more information.

Highlighter, freehand highlighter
Rubber stamp
Rectangle, ellipse, line, connected lines
Arrow
Freehand drawing
Link
Ruler, polygon ruler
Text
Sticky note

DEMO

Annotate and comment on your documents online

Try it live. Upload any document and test the full annotation toolkit — highlight text, add comments, draw shapes, and collaborate in real time. No signup required.

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Integration

Works with your entire tech stack. Integrate seamlessly and deploy on your infrastructure in minutes.

ASP.NET Web Forms, ASP.NET MVC Razor, ASP.NET Core
Other web technologies: Angular, AngularJS, Node.js, Blazor, React, Java, PHP, JavaScript/jQuery, SharePoint