PDFSign
PDFSign is a Windows desktop application for securely signing, editing, managing and processing PDF documents. It supports DSC-based digital signing, allowing users to sign individual or multiple PDF files in batch. AutoSign provides automated signing workflows through two modes: Batch Review and Watch Folder, enabling users to configure signing rules and automatically process incoming PDF documents.
PDFSign also includes a comprehensive PDF Toolbox with tools to merge, split, reorder, extract, rotate, crop, compress and repair PDFs; edit text; add text and images; annotate, highlight and redact documents; add watermarks, headers/footers and page numbers; perform OCR; convert between PDF and common document/image formats; and fill forms.
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Adobe PDF Library SDK
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.
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FixMyPDF
FixMyPDF is a privacy-first, free online PDF toolkit offering 70+ tools to convert, organize, secure, optimize, and edit PDF files. All processing is 100% browser-based—no file uploads, no registration required, and no data tracking. Features include compressing PDFs, converting images (JPG, PNG, SVG, etc.) to PDF and vice versa, editing metadata, adding or removing password protection, splitting & merging, text extraction, watermarking, annotation editing, and much more. Used by over 10,000 users and processing 100,000+ files with a 4.9★ rating.
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pdfRest
pdfRest is a developer PDF API with 40+ endpoints for conversion, extraction, and document manipulation. Convert to and from PDF (Word, Excel, PowerPoint, images, PDF/A, PDF/X). Merge, split, compress, and linearize. Extract text, images, and metadata. Add OCR to scanned documents. Watermark, encrypt, decrypt, restrict, and redact. Fill, flatten, import, and export form data. Requests are chainable, so multi-step document pipelines run in sequence without shuttling files back and forth between calls.
What sets pdfRest apart in the PDF API space is deployment flexibility. Most PDF APIs are cloud-only. pdfRest ships three ways: Cloud, Container and AWS Marketplace.
For teams running an evaluation: pdfRest is SOC 2 Type 2 audited and supports GDPR and HIPAA requirements. The Container deployment is the strongest fit for regulated workloads, specifically because processing happens entirely inside your own environment.
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