Syncfusion and Kernstra both publish a price. One is priced per developer, the other per app.

PDF Viewer SDK $599 per developer a year, including Business Support (the default), per developer from one developer, up to 50 before a custom quote; 10,000 end users a year included, scaled up in blocks of 100,000 and 1 million; each product a separate license; Document SDK $1,199 per developer a year; minimum one-year subscription, annual commitment required, paid yearly or in twelve monthly installments; 30-day free evaluation; the UI Component Suite is listed as 1,600+ UI components. Not in the page’s visible text, the pricing calculator’s data gives $399 per developer with Standard Support and $799 with Enterprise Support; each further 100,000 end users a year $995 (Standard), $1,495 (Business) or $1,995 (Enterprise), each further 1 million $4,995, $6,995 or $9,995; and a 7.5% Quick Closing Discount for buying within the evaluation.

Free access to all of Essential Studio, PDF Viewer SDK included, for companies and individuals with under $1M annual gross revenue, 5 or fewer developers and 10 or fewer employees, never more than $3M of outside capital; government-funded organizations not eligible.

Platforms (Blazor, React, Angular, JavaScript, Vue, ASP.NET Core and MVC, .NET MAUI, WPF, WinForms, UWP, Flutter); annotations, form filling, form designer, handwritten, typed and image signatures, redaction, page organizer, comment threads, real-time collaboration, side-by-side comparison; processing inside your application unless optional backend features are enabled; touch support in mobile browsers.

Progressive and on-demand page loading; its FAQ says modifying existing text or images typically needs additional PDF processing tools or backend services.

Certificate-based signing and validation marked supported for JavaScript, React, Angular and Vue; advanced PKI-based signing and verification are enabled through integration with the Syncfusion PDF Library.

The JavaScript PDF Library, which applies digital signatures, is part of Syncfusion’s Document SDK, licensed separately from the PDF Viewer SDK (its license’s Schedule B lists the Document SDK as document processing libraries and the PDF Viewer SDK as PDF Viewer components).

A Syncfusion code example of the React PDF Viewer component in a Next.js application.

The standalone viewer loads its PDFium resource files (resourceUrl) from a CDN or a self-hosted folder.

Server-backed mode renders on a web service you host (serviceUrl); from 2026 Volume 2 no new features are added to it, since almost all functionality is in the standalone viewer.

Multiple replies to a comment, and a status set on a comment or reply.

Real-time editing of annotations, form fields and pages through its Collaborator framework and a Collaboration Server (on Node.js, over WebSocket, with Redis).

A built-in toolbar to add text box, check box, radio button, list, signature and other fields.

Once applied, redaction permanently removes the selected content; it cannot be undone.

Insert, delete, rotate, reorder and import pages.

Distance, perimeter, area, radius and volume measurements, with a scale ratio.

WCAG 2.2 and Section 508 support marked "Yes" (no conformance level stated); mobile device support "Intermediate".

Web PDF Viewer: collaborative editing, link annotations, text stamps, semantic text comparison (added, deleted, modified), active viewport rendering, WebMCP tools for AI agents.

Summarization with questions and answers, Smart Redaction and Smart Fill, powered by an AI service such as Azure OpenAI.

OCR for scanned PDFs; Word, Excel, PowerPoint and HTML to PDF conversion.

Syncfusion and its Bold product lines are SOC 2 Type 2 certified, audited annually over 12 months; the report is available to current and prospective customers on request.