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Different brands are not always different options.

This index lists 155 tools. A number of them are owned by the same company, and you would not know it from the names on the page. When two products share an owner, choosing between them is a choice between two products from one vendor — which is worth knowing before you treat them as independent alternatives.

Companies with more than one tool here

Apryse

12 tools

  • Apryse Commercial PDF SDK best known for WebViewer, its in-browser document SDK.
  • iText Java and .NET PDF library with an AGPL-3.0 core and component-specific licensing.
  • LEADTOOLS PDF SDK Commercial PDF SDK for .NET, C++ and mobile targets, with OCR, forms, conversion and automatic redaction alongside the PDF API.
  • PDF Studio Perpetual-licence PDF editor for Windows, Mac and Linux, now sold as Xodo PDF Studio.
  • PDFlib Long-standing commercial library for generating PDFs, with page-import and personalisation tiers.
  • Pdftools PDF Viewer SDK Client-side PDF viewer SDK for web and mobile, with true redaction built in.
  • Pdftools SDK Commercial SDK for PDF/A conversion, validation, compression and signing at volume.
  • PrizmDoc Accusoft's document viewing and processing APIs, with permanent redaction and AI-assisted PII detection, self-hosted or hosted.
  • Qoppa Java PDF SDK Java PDF library suite that is no longer sold: its functionality moved to Apryse Java PDF.
  • Scanbot SDK Commercial on-device SDK for mobile scanning, barcodes and data capture.
  • Solid Framework PDF-to-Office conversion SDK that is no longer sold separately: its technology moved into the Apryse SDK.
  • Xodo Apryse's cross-platform PDF suite: browser tools, a desktop editor and mobile apps.

Artifex Software

5 tools

  • DocRaptor Hosted HTML-to-PDF API built on the Prince engine, with CSS Paged Media and tagged accessible output.
  • Ghostscript PostScript and PDF interpreter and SDK for converting, rasterising and compressing.
  • MuPDF (mutool) Fast C PDF library plus the mutool command-line suite.
  • MuPDF.js Artifex's WebAssembly build of the MuPDF engine for JavaScript and browsers.
  • PyMuPDF Fast Python document library built on MuPDF, with genuine destructive redaction.

Allyant

3 tools

  • Allyant PDF Validator Free Acrobat plug-in accessibility checker that tests a PDF against WCAG and PDF/UA and guides manual testing.
  • CommonLook Office Windows add-in that generates accessible PDFs from Word and PowerPoint and walks the author through the checkpoints.
  • CommonLook PDF AI-assisted PDF accessibility remediation in the browser or on the desktop, with PDF/UA, WCAG and HHS validation.

Avanquest

3 tools

  • PDF Architect Modular Windows PDF editor from the PDFCreator team, with real redaction.
  • PDFescape Long-running free browser PDF editor and form filler, with paid desktop tiers.
  • Soda PDF Subscription PDF suite with a Windows app, a browser edition and online AI tools.

axes4 GmbH

3 tools

  • axesCheck Free browser-based PDF/UA and WCAG accessibility checker that needs no installation.
  • axesPDF Windows desktop accessibility checker and fixer for tagged PDFs, with PDF/UA machine checks and one-click repairs.
  • PAC Free Windows accessibility checker for PDF/UA and WCAG, with local AI-assisted semantic checks.

callas software GmbH

3 tools

  • pdfaPilot PDF/A and PDF/UA conversion, validation and correction for archiving and accessibility.
  • pdfGoHTML Free Acrobat plug-in that renders a tagged PDF as structured HTML, so a person can judge its accessibility and tagging.
  • pdfToolbox Preflight, correction and PDF standards validation, including PDF/UA accessibility checks.

Aspose Pty Ltd

2 tools

  • Aspose.PDF Commercial PDF library and API for .NET, Java, C++ and Python, sold under a perpetual per-developer licence.
  • GroupDocs Document SDK family for .NET, Java, Node.js and Python, from the company behind Aspose.

Datalogics

2 tools

  • Adobe PDF Library Commercial PDF SDK built on Adobe's own engine, sold and supported by Datalogics.
  • pdfRest REST API for PDF processing built on Adobe PDF Library, with a self-hosted option.

Endless Labs, Inc. dba Datalab

2 tools

  • Marker PDF-to-Markdown converter built around a vision-language model, sold by Datalab as an open-source tool and a paid hosted API.
  • Surya Open document OCR and layout model that returns text, reading order and tables as structured output.

Orpalis Imaging SAS

2 tools

  • AvePDF Free EU browser PDF toolkit, operated by the company behind the Nutrient SDK.
  • Nutrient Commercial PDF SDK with a client-side web SDK and self-hosted document engine.

Sensus ApS

2 tools

  • RoboBraille Free email and web service that converts documents into accessible formats: Braille, audio, e-books and tagged PDF.
  • SensusAccess Self-service conversion of documents into accessible formats, and remediation of inaccessible PDFs.

Setasign GmbH & Co. KG

2 tools

  • FPDI PHP library that imports pages from existing PDFs into FPDF, mPDF, TCPDF and tFPDF templates.
  • SetaPDF-Core Commercial PHP library giving low-level access to PDF objects, metadata and encryption.

The Apache Software Foundation

2 tools

  • Apache FOP Java XSL-FO formatter that turns XML formatting objects into PDF and print output.
  • Apache Tika Java toolkit that detects and extracts text and metadata from over a thousand file formats through one interface.

Tracker Software Products

2 tools

One tool each

Where the operating company differs from the brand you see on the product.

Why this matters

  • — Licence terms travel with the owner. Apryse's SDK licence forbids distributing it as a stand-alone PDF application that could compete with an Apryse product — and Apryse owns Xodo and PDF Studio, both listed here. A restriction on one product can reach a brand you did not connect to it.
  • — Consolidation changes what competition means. When several "alternatives" share a parent, switching between them does not change who holds your documents or sets your terms.
  • — Free tools can be funnels. A free product and a paid commercial one under the same owner are not always independent of each other.

Every owner here is recorded on the individual tool page and comes from that vendor's own privacy policy, site footer, licence agreement or app store record, listed in the record's sources. Ownership changes: if you believe one of these is wrong or out of date, the corrections route is open.