Best On-Premises PDF Annotators

Apryse (formerly PDFTron) powers the future of document technology. We help businesses, developers, and enterprises handle documents with unmatched speed, accuracy, and security. Whether running in secure server environments or delivering seamless web-based experiences, Apryse makes document workflows smarter and easier. With Apryse, you can: Embed powerful document features directly into your apps — from viewing and editing to collaboration and compliance. Run at enterprise scale on secure server infrastructure, ensuring reliability without cloud dependencies. Deliver seamless in-browser document experiences with responsive, accessible, and feature-rich web capabilities. Trusted globally, Apryse empowers organizations to simplify operations, enhance productivity, and create exceptional document experiences.

Nutrient SDK brings in-app PDF annotation and markup to document review, so users mark it up where it lives instead of exporting files to a separate review tool. Developers, product managers, and document review teams use it for contract and compliance review, board packs, blueprint and engineering markup, and approval workflows. It offers more than 15 spec-compliant annotation types, including highlights, underlines, strikeouts, ink, shapes, stamps, sticky notes, and free text, that render consistently across web, mobile, and desktop. Threaded comments attach to annotations, record author and time, and can be resolved or reopened, while permissions control who can view, comment on, or edit annotations. Teams can customize colors, toolbars, and stamps, query and manage annotations through the API, and export to XFDF for other PDF tools or Instant JSON for syncing across users and devices.

Add a fully functional PDF editor to your ASP.NET website in minutes! Compatible with 99% of desktop & mobile browsers, from Internet Explorer 6 through the latest iOS Safari release, RAD PDF simply works. No plugins or other software needed. RAD PDF natively supports the most commonly used PDF features. Beyond a PDF reader, RAD PDF equips web applications with a browser-based PDF editor & PDF annotator. Features not even available in Adobe Acrobat Reader can be used to provide advanced PDF functionality. By enabling PDF form filling, PDF redaction, & PDF signing directly in the web browser, RAD PDF users can utilize PDF features without worrying about having the right platform or software installed! Allow your app to design new PDF forms, protect content, sign PDFs, & more using an intuitive graphical user interface (GUI). Client (JavaScript) and server APIs allow for endless possibilities .NET Core, Framework, & .NET 5+ supported Try editing any PDF with RAD PDF, FREE!

Adobe PDF Library is the only commercial PDF SDK built on Adobe Acrobat's own core engine, delivering the same rendering accuracy, PDF spec coverage, and behavior as Acrobat itself. Available in Modern C++, Adobe C/C++, .NET, .NET Framework, and Java, and supported on Windows, macOS, and Linux. Create, edit, merge, split, annotate, and watermark PDFs programmatically; convert to and from Word, Excel, PowerPoint, PDF/A, PDF/X, and more; add OCR, digital signatures, redaction, and encryption; and process AcroForms and XFA forms. SOC 2 Type 2 compliant, with a 91% customer retention rate among enterprise users. For enterprise deployment, the pdfRest API Toolkit Container packages this technology as a self hosted REST API for on premises, private cloud, or hybrid environments. Datalogics also offers Scout, an AI assistant, and an MCP server so teams can bring PDF capabilities into AI powered workflows.