veraPDF
Free Open-Source PDF/UA Validator Built into PDFix
Validate PDF/UA-1, PDF/UA-2, WCAG 2.2 and PDF/A – locally, free, backed by the PDF Association and the Open Preservation Foundation.
PDF/UA · Open Source · Industry Supported · ISO-endorsed
DEFINITION
What is veraPDF?
veraPDF is a purpose-built validator designed to verify compliance with PDF/UA and PDF/A standards. It is developed by the Open Preservation Foundation and the PDF Association – the same organizations that author and maintain the ISO standards veraPDF tests against.
Unlike proprietary validators, veraPDF’s validation logic is open source. Any user can inspect exactly how and why a document passes or fails a specific rule – no black box, no vendor interpretation.
PDFix chose veraPDF as the core validation engine for all its products because the results are authoritative, reproducible and trusted globally by national libraries, government archives and accessibility professionals.
How veraPDF validates – 4-layer approach
- Parse the complete PDF structure — tags, metadata, objects
- Load document objects into veraPDF’s validation model
- Apply rules from the selected profile – PDF/UA-1, PDF/UA-2, WCAG
- Compile results into RAW, HTML, TEXT, XML or JSON report
Matterhorn Protocol
The Matterhorn Protocol defines 31 checkpoints and 136 failure conditions for PDF/UA-1 compliance. veraPDF implements the complete protocol.
DOWNLOAD & INSTALL
How to install veraPDF
veraPDF provides multiple deployment options to fit different workflows. No separate download required when using PDFix: Desktop and SDK embed the veraPDF engine directly.
Desktop UI
veraPDF application provides a user interface similar to PAC (PDF Accessibility Checker) for users who prefer visual tools.
CLI
Command-line interface for automation and batch processing. The approach PDFix uses for SDK integration.
Docker
Containerized veraPDF CLI for cloud and on-premises pipelines. PDFix provides a ready-to-use Docker configuration.
Web Validator
Official online validator from the veraPDF project- veraPDF Web Demonstrator. No installation required for a quick check.
VALIDATION PROFILES
veraPDF validation profiles
PDF/UA-1, PDF/UA-2, WCAG
Choose the standard that matches your compliance requirement.
PDF/UA-1
ISO 14289-1 · Matterhorn Protocol · most widely enforced
PDF/UA-2
ISO 14289-2 · PDF 2.0 aligned · newer standard
Well-Tagged PDF
WTPDF · structural tagging quality profile
veraPDF on GitHub
All veraPDF validation profiles
CLI QUICK GUIDE
veraPDF CLI – command line examples
Run veraPDF from the command line for automation, batch processing and CI/CD integration.
Validate a single PDF file – PDF/UA-1 or WCAG
verapdf --flavour ua1 file.pdf
verapdf --profile /path/to/profile.xml file.pdfValidate multiple files
verapdf --format xml --flavour ua1 file1.pdf file2.pdfOutput formats: HTML, XML, JSON, text, raw
verapdf --format xml --flavour ua1 file.pdf
verapdf --format html --flavour ua1 file.pdfPDF/UA-1 VALIDATOR COMPARISON
Why veraPDF, PAC, Adobe and CommonLook report different errors
In a study of 155 PDF files, four leading validators produced inconsistent results in 50.3% of cases.
Different PDF/UA validators interpret the same ISO 14289-1 clause differently – the same document can pass one tool and fail another. The full comparison table maps error messages from veraPDF, PAC, Adobe Preflight, and CommonLook side by side so you can identify exactly where they disagree and why.
UNDERSTANDING RESULTS
How to read a veraPDF validation report
Clause / Rule ID – the standard requirement
Maps the issue to a specific requirement in the ISO standard or Matterhorn Protocol checkpoint. Use this to identify the violated rule.
e.g. 6.1.2-1
Description – what failed and why
A plain-language explanation of what failed. Examples: “missing tag”, “no Alt attribute on figure element”, “document language not set”.
e.g. “missing tag”
Object Reference – where in the document
Points to the exact problematic PDF object – page number, object ID, and structure tree location. Jump directly to the issue in your PDF editor.
e.g. page 3 / obj 42
PDF/UA VALIDATION ERRORS
Found a validation error? Here is how to fix it.
Every PDF/UA-1 error reported by veraPDF, PAC, or Adobe Preflight can be fixed in PDFix Desktop.
How fixes work
PDFix Desktop offers three fix types for every validation error – Auto-Fix, Semi-Auto, and Manual. The Validation panel pre-selects the problematic objects, so the fix applies to the specific error – not the whole document.
How to use this guide
Every error maps to a clause in ISO 14289-1. Note the clause number from the Validation panel – for example 7.1-9 – find it in the reference table, and click it.
Each clause opens the rule description and a step-by-step fix guide for PDFix Desktop.
START VALIDATING – FREE
Start using veraPDF today
Free PDF Validator PDFix Desktop Lite
Lite embeds the full veraPDF engine – validate PDF/UA-1, PDF/UA-2, and WCAG 2.2 with no CLI configuration, no Docker, no license, and no cost. A free PDF accessibility checker.
To fix validation issues, download PDFix Desktop Pro – a full PDF remediation tool. The only trial limitation is a watermark after saving.
