# Validating PDF/UA Documents in .NET C#: A Practical Guide > This article explains how to validate PDF/UA documents in .NET C# using the TXTextControl.PDF.Validation NuGet package. It shows how to inspect validation status, generate JSON reports, handle signed PDFs as diagnostics, and block encrypted PDFs. - **Author:** Bjoern Meyer - **Published:** 2026-07-06 - **Modified:** 2026-07-06 - **Description:** This article explains how to validate PDF/UA documents in .NET C# using the TXTextControl.PDF.Validation NuGet package. It shows how to inspect validation status, generate JSON reports, handle signed PDFs as diagnostics, and block encrypted PDFs. - **10 min read** (1841 words) - **Tags:** - ASP.NET - ASP.NET Core - PDF - Accessibility - PDF/UA - **Web URL:** https://www.textcontrol.com/blog/2026/07/06/validating-pdf-ua-documents-in-dotnet-csharp/ - **LLMs URL:** https://www.textcontrol.com/blog/2026/07/06/validating-pdf-ua-documents-in-dotnet-csharp/llms.txt - **LLMs-Full URL:** https://www.textcontrol.com/blog/2026/07/06/validating-pdf-ua-documents-in-dotnet-csharp/llms-full.txt --- PDF is still the format many organizations use for invoices, contracts, statements, forms, reports, manuals, and archived business documents. A PDF that looks correct on screen, however, is not automatically accessible. For someone using a screen reader, a braille display, keyboard navigation, or magnification software, the file also needs a structure that software can interpret. That is where PDF/UA comes in. PDF/UA is the ISO standard for accessible PDF documents. It describes how a PDF should expose tags, reading order, language, alternate text, tables, forms, metadata, and other information required by assistive technology. For .NET C# developers, the practical question is not only what PDF/UA means. The real question is how to check the PDFs your application creates before they reach customers, auditors, or public websites. > **PDF/UA Validation in .NET** > > The TXTextControl.PDF.Validation NuGet package returns structured PDF/UA validation reports that can be used in document generation, QA, and automated publishing workflows. ### What PDF/UA Means in Practice PDF/UA stands for PDF/Universal Accessibility. The standard is published as ISO 14289 and focuses specifically on accessibility inside the PDF file format. [PDF/UA-1](https://pdfa.org/resource/iso-14289-pdfua/) is still a common production target and is based on PDF 1.7. [PDF/UA-2](https://pdfa.org/iso-14289-2-pdfua-2/) is newer and aligns with PDF 2.0. In everyday development work, PDF/UA means the document must be more than a visual page description. It needs a tagged structure tree, a logical reading order, document language, a title, Unicode text mapping, alternate descriptions for meaningful images, usable table semantics, and accessible form fields. PDF/UA is also different from [WCAG](https://www.w3.org/WAI/standards-guidelines/wcag/). WCAG covers accessibility more broadly across web and digital content. PDF/UA covers the technical PDF layer: whether the file carries the structure that PDF readers and assistive technologies need. A strong accessibility workflow usually considers both, but PDF/UA is the standard that answers whether the PDF itself is engineered correctly. ### Why Validate PDF/UA Automatically? PDF accessibility problems are often invisible in a visual review. A heading can look like a heading but be tagged as a paragraph. A table can look organized but have no header relationships. A form field can have a visible label while missing an accessible tooltip. An image can be placed perfectly on the page but have no alternate text in the structure tree. Automated validation catches many of these issues early. It is especially useful when PDFs are generated from templates, merged from data, or produced as part of a server-side process. Instead of waiting for a manual accessibility review at the end, you can make PDF/UA validation part of development, QA, or CI/CD. This is most valuable for repeatable document workflows: Invoices, statements, reports, customer letters, policy documents, accessible forms, and any process where one template can generate thousands of PDFs. Fixing the template or generation logic improves every future document. ### Installing the NuGet Package The validator is distributed as the [TXTextControl.PDF.Validation](https://www.nuget.org/packages/TXTextControl.PDF.Validation) NuGet package. Add the package reference to your application project: ``` ``` After adding the package, the validator can be used from any .NET application that has access to a PDF file or a PDF byte array. ### Validating a PDF File The main entry point is PdfUaValidator.Validate. It returns a structured Report object that contains the overall validation status, PDF/UA findings, extracted document information, and diagnostics for signatures and encryption. ``` using TXTextControl.PDF.Validation; using TXTextControl.PDF.Validation.Model; Report report = PdfUaValidator.Validate("invoice.pdf"); Console.WriteLine(report.Status); foreach (Finding finding in report.Findings) { Console.WriteLine($"{finding.Severity} {finding.RuleId}: {finding.Message}"); } ``` If the PDF is already in memory, use the byte-array overload. This is useful in server-side document generation workflows where the PDF is created and validated before it is written to disk, sent to the browser, or archived. ### Understanding the Result The most important property is Status. A report can be Passed, CompletedWithWarnings, Failed, or Blocked. A blocked report means validation could not fully run, for example because the PDF is encrypted. For simple integrations, report.IsPass is also available. It returns true for passed reports and reports completed with warnings. It returns false for failed or blocked reports. Each finding has a rule ID, category, severity, pass/fail value, and message. This makes it possible to show a developer-friendly report while still keeping stable identifiers for automation. ### JSON Reports for Pipelines and QA Most production workflows need more than a console message. They need data that can be stored, compared, or attached to a build artifact. The validator can serialize the report to JSON, including the status, findings, extracted tables, links, figures, forms, standards declarations, and document diagnostics. A common usage pattern is to reject generated PDFs when validation fails or is blocked: ``` using TXTextControl.PDF.Validation; using TXTextControl.PDF.Validation.Model; Report report = PdfUaValidator.Validate("statement.pdf"); if (report.Status is ValidationStatus.Failed or ValidationStatus.Blocked) { string json = PdfUaValidator.ToJson(report, indented: true); File.WriteAllText("statement-validation.json", json); throw new InvalidOperationException( $"PDF/UA validation did not pass. Status: {report.Status}"); } ``` This is useful in CI/CD pipelines and automated quality checks. If a template change removes alternate text, breaks form labeling, or drops the document language, the build can catch it before the document ships. ### What the Validator Looks For The validator checks the main areas developers usually need to verify in generated PDFs. It inspects metadata, language, the tagged PDF marker, structure tree, role mapping, fonts, ToUnicode maps, alternate descriptions, links, forms, tables, embedded files, annotations, optional content, XFA, security, actions, and XObjects. That sounds broad, but the goal is simple: Confirm that the PDF contains the machine-readable structure an accessible PDF needs. The report groups findings into checkpoint categories so developers can see whether a problem belongs to metadata, natural language, fonts, structure, forms, tables, or another area. Some findings are hard failures, such as missing required accessibility structures. Others are warnings or informational review signals when the validator can detect a condition that may need human judgment. ### Signed PDFs Digital signatures are common in contracts, approvals, and forms. They are important, but they are not PDF/UA requirements. A document can have a valid signature and still fail accessibility validation. It can also be accessible while a signature diagnostic reports a problem. For that reason, signature information is kept separate from PDF/UA findings under report.Diagnostics.Signatures. The diagnostics include signature integrity, whole-document coverage, signer subject, signing time, ByteRange values, and verification details. These results help you understand the document state without mixing signature validity into the accessibility pass/fail result. ### Encrypted and Password-Protected PDFs Encrypted PDFs are handled differently. A password-protected PDF must be decrypted before its tags, streams, metadata, form labels, and alternate text can be reliably inspected. This validator does not decrypt PDFs and does not include an external PDF decryption engine. If encryption is detected, the report status becomes Blocked, IsPass is false, and validation stops before content-level PDF/UA checks run. This avoids the dangerous situation where an encrypted document receives a false accessibility pass based on incomplete inspection. ### Using the Package in an Application In most applications, validation runs directly after a PDF is generated or received. A document service can validate the file, store the JSON report, and decide whether the PDF is allowed to continue through the workflow. ``` using TXTextControl.PDF.Validation; using TXTextControl.PDF.Validation.Model; public sealed class PdfAccessibilityService { public Report ValidateGeneratedPdf(byte[] pdfData, string reportPath) { Report report = PdfUaValidator.Validate(pdfData); string json = PdfUaValidator.ToJson(report, indented: true); File.WriteAllText(reportPath, json); return report; } } ``` For web applications, the same pattern can be used after generating a PDF response but before sending it to the client. For background services, it can run as a quality gate before a document is archived, emailed, or handed off to another system. ### When to Use This Validator Use this validator when PDF accessibility needs to be checked programmatically in a .NET application. It is a good fit for server-side PDF generation, document automation, invoice and statement workflows, accessible forms, template validation, and QA checks before publishing PDFs. It is also useful when a team needs JSON output rather than a purely interactive accessibility checker. A support team can attach validation reports to tickets. A QA team can compare reports between releases. A build pipeline can fail when generated PDFs become inaccessible. ### Automated Validation Still Needs Human Review Although automated validation is essential, it is not the only step in the accessibility process. Some questions require human judgment. Alternate text may exist but still be unhelpful. The reading order may be technically present but confusing. A table may have tags but still fail to communicate the correct relationships. Link labels may pass automated checks while remaining unclear to users. The best results are achieved when accessible documents and templates are created using a visual editor, such as TX Text Control. A visual editing environment allows you to see the actual document while you define the reading order, place content, create tables, and write meaningful text alternatives. Rather than working directly with markup or tags, authors can verify the accessibility of content in context. This makes it much easier to produce documents that are technically compliant and genuinely usable. The best workflow combines both approaches. Use automated validation as a repeatable technical gate. Use a visual editor to create and refine accessible documents. Perform a manual review for semantics, user experience, and high-value public documents. ### Conclusion PDF/UA validation turns accessible PDF generation into something measurable. It helps developers catch missing tags, missing language metadata, unlabeled forms, image description problems, table issues, and other accessibility defects before documents reach users. TXTextControl.PDF.Validation brings that workflow into .NET C# applications with a simple API, structured reports, JSON output, signature diagnostics, and clear blocked handling for encrypted PDFs. If your application creates or processes PDFs, a PDF/UA validator should be part of the pipeline. It moves accessibility from a late manual check into a repeatable engineering step. ### Frequently Asked Questions What is PDF/UA validation? --------------------------- PDF/UA validation checks whether a PDF contains the technical accessibility information required by the PDF/UA standard, including tags, language, metadata, alternate descriptions, form information, and structural relationships. Can PDF/UA validation be automated in .NET C#? ----------------------------------------------- Yes. TXTextControl.PDF.Validation can be used directly in .NET applications to validate PDF files or byte arrays and return a structured report that can be inspected in code or serialized to JSON. Does a passed PDF/UA validation replace manual accessibility review? --------------------------------------------------------------------- No. Automated validation is an important technical gate, but some accessibility questions require human judgment, such as whether alternate text is meaningful or whether the reading order makes sense to users. How are signed PDFs handled? ----------------------------- Signed PDFs can still be validated for PDF/UA. Signature information is reported separately as document diagnostics, so signature validity does not change the PDF/UA pass or fail result. --- ## About Bjoern Meyer As CEO, Bjoern is the visionary behind our strategic direction and business development, bridging the gap between our customers and engineering teams. His deep passion for coding and web technologies drives the creation of innovative products. If you're at a tech conference, be sure to stop by our booth - you'll most likely meet Bjoern in person. With an advanced graduate degree (Dipl. Inf.) in Computer Science, specializing in AI, from the University of Bremen, Bjoern brings significant expertise to his role. In his spare time, Bjoern enjoys running, paragliding, mountain biking, and playing the piano. - [LinkedIn](https://www.linkedin.com/in/bjoernmeyer/) - [X](https://x.com/txbjoern) - [GitHub](https://github.com/bjoerntx) --- ## Related Posts - [AI Generated PDFs, PDF/UA, and Compliance Risk: Why Accessible Document Generation Must Be Built Into the Pipeline in C# .NET](https://www.textcontrol.com/blog/2026/03/23/ai-generated-pdfs-pdf-ua-and-compliance-risk-why-accessible-document-generation-must-be-built-into-the-pipeline-in-c-sharp-dot-net/llms.txt) - [Validate Digital Signatures and the Integrity of PDF Documents in C# .NET](https://www.textcontrol.com/blog/2025/11/14/validate-digital-signatures-and-the-integrity-of-pdf-documents-in-csharp-dotnet/llms.txt) - [Validate PDF/UA Documents and Verify Electronic Signatures in C# .NET](https://www.textcontrol.com/blog/2025/11/13/validate-pdf-ua-documents-and-verify-electronic-signatures-in-csharp-dotnet/llms.txt) - [Automating PDF/UA Accessibility with AI: Describing DOCX Documents Using TX Text Control and LLMs](https://www.textcontrol.com/blog/2025/10/16/automating-pdf-ua-accessibility-with-ai-describing-docx-documents-using-tx-text-control-and-llms/llms.txt) - 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