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3-Heights® PDF to PDF/A Converter - convert PDF to PDF/A in C#, Java & Batch for long-term digital archiving

The 3-Heights® PDF to PDF/A Converter is a component for converting PDF documents into the PDF/A format for long-term archiving. This component is both robust and scalable, making it suitable for integration in various processes such as standardization, quality assurance and archive migration. The PDF to PDF/A Converter comes in different variants: as Shell to be used with the command line, as watched folder service and as API to be used with C#, Visual Basic, Java, C/C++.

PDF/A Converter

Bulk convert PDF to PDF/A, ensuring ISO standard compliance and searchable text via OCR (optional)

PAdES Digital Signature

Add PDF/A-conform long-term digital signature and embed metadata

Digital Archiving

Integration into archiving systems with quality assurance and support regarding document conformance to legal requirements


Paperless electronic file management at the cantonal tax administration authority

The electronic archive at the cantonal tax administration authority of Thurgau was introduced in pursuit of a paperless electronic file management system. Comprehensive file management of documents is intended to boost efficiency and enable a standardized archiving process.

Encryption of customer reports to meet compliance requirements at Bank Hapoalim

Compliance requirements at Bank Hapoalim require that documents are protected against changes when reporting to customers. Tests revealed that the 3-Heights™ PDF to PDF/A Converter is able to guarantee extremely high conversion quality.
3-Heights® PDF to PDF/A Converter - Document Archiving

PDF to PDF/A Converter - Features

  • Convert PDF documents to PDF/A-1, PDF/A-2, PDF/A-3
    • Support for all PDF/A conformance levels
    • Make color spaces device-independent, e.g. by embedding ICC profile or setting an output intent
    • Embed and subset fonts
    • Colorants management (PDF/A-2 and later)
    • Recover corrupt documents
    • Repair corrupt data such as embedded font programs or images
    • Remove transparency (PDF/A-1 only)
    • Remove malicious content such as attached files (PDF/A-1 and PDF/A-2) and JavaScript actions
    • Remove multimedia content such as video and sound
    • Conversion of embedded and attached files (PDF/A-2 and later)
    • Repair metadata and make them consistent
  • Conversion process control
    • Pre- and post-validation
    • Conversion reporting
    • Write the application log to a log file
    • Automatically determine optimal conformance based on input file (optional)
    • Enables sophisticated error handling
  • Digital signatures, PDF/A-conform
    • Apply PAdES-LTV (Long Term Validation) signatures
    • Embedded trust chain, time-stamp and revocation information (OCSP, CRL)
    • Various types of cryptographic providers
      • Windows certificate store
      • Hardware such as hardware security module (HSM), smart cards, and USB tokens
      • Online signature services
        • QuoVadis sealsign
        • Swisscom All-in Signing Service
        • GlobalSign Digital Signing Service
    • Mass signing of documents
    • Add an optional visual appearance of the signature (page, size, color, position, text, background image, etc.)
  • Read input from and write output document to file, memory or stream
  • Read encrypted input files
  • Enhance output file
    • Set metadata
    • Linearization for fast web view
    • Use PDF file compression features (PDF/A-2 and later)
  • Text recognition using OCR engine (optional)
    • Replace old OCR text or skip images with existing OCR text
    • Set the OCR language and options
    • Deskew and de-noise images
    • Detect barcodes
    • List OCR plug-ins
  • Add embedded files (PDF/A-2) and associated files (PDF/A-3)
  • Embedded XML invoice data conforming to the ZUGFeRD specification (PDF/A-3)


  • Standards:
    • ISO 32000-1 (PDF 1.7)
    • ISO 32000-2 (PDF 2.0)
    • ISO 19005-1 (PDF/A-1)
    • ISO 19005-2 (PDF/A-2)
    • ISO 19005-3 (PDF/A-3)
    • PAdES (ETSI EN 319 142) signature levels B-B, B-T, CMS
    • Legacy PAdES baseline signature (ETSI TS 103 172) B-Level and T-Level
    • Legacy PAdES (ETSI TS 102 778) Part2 (PAdES Basic), Part3 (PAdES-BES), and Part4 (PAdES-LTV, Long Term Validation)
    • Long term signature profiles for PAdES (ISO 14533-3)
    • Cryptographic Suites (ETSI TS 119 312)
    • ZUGFeRD 1.0, 2.0, 2.1 (2.1.1) Factur-X 1.0
  • Quality assurance: veraPDF test corpus and Isartor test suite
Powered by 3‑Heights® TechnologyPDF/A compliant

Supported formats

Input Formats

  • PDF 1.0 to 1.7
  • PDF 2.0

Output Formats

  • PDF/A-1a*, PDF/A-1b
  • PDF/A-2a*, PDF/A-2b, PDF/A-2u
  • PDF/A-3a*, PDF/A-3b, PDF/A-3u

*) The input file must fulfill the relevant conditions for PDF/A creation.

Areas of use - PDF conversion to PDF/A

Incoming mail

All incoming PDF documents can be converted directly to PDF/A for long-term archiving. Documents that cannot be converted can be rejected as soon as they are received by email. This increases process quality and reduces the need for subsequent quality controls.


The converter processes documents from all corporate business areas during archiving. It quickly and easily converts documents worthy of retention into PDF/A and verifies conformity of the result with the ISO standard. It therefore acts as a gatekeeper, ensuring that only conform files find their way into business processes or a long-term archive.

Other areas of use

  • Standardization
  • Quality assurance
  • Conformance with legal requirements
Contact us

Convert PDF document to PDF/A

Convert a PDF document to a specific PDF/A compliance level such as PDF/A-2u. Allow for automatic downgrade, e.g. to PDF/A-2b, if the input file cannot be converted otherwise.

C# sample:
// Create the converter
using (Pdf2Pdf converter = new Pdf2Pdf())
    // Set compliance level
    converter.Compliance = compliance;
    converter.AllowDowngrade = true;

    // Convert to PDF/A
    if (!converter.Convert(inputPath, "", outputPath, ""))
        throw new Exception(String.Format("Input file {0} could not be converted. " + 
            "{1} (ErrorCode: 0x{2:x}).", inputPath, converter.ErrorMessage, converter.ErrorCode));
C# sample:
The caveats of assembling PDF/A documents

The caveats of assembling PDF/A documents

Assembling PDF documents from various sources is a crucial part of an output management system. And, as the document needs to be archived in most cases, it should conform to the PDF/A standard. Is there a way to assemble a document and accomplish PDF/A conformance in one step?
Converting invoice documents to the ZUGFeRD data format

Converting invoice documents to the ZUGFeRD data format

XML or PDF? That's one of the most heard questions when it comes to invoice document formats. XML is the preferred format for machines whereas PDF is the format for humans. But why not have the cake and eat it? With ZUGFeRD you can have both documents in one file.

Further product details

The 3-Heights® PDF to PDF/A Converter first analyzes the input file based on the level of conformity (Level A, B or U). Conversion to the highest possible level of conformity is then carried out with the aid of the result from the analysis. There is also an option to carry out an analysis of the output document.

The conversion process embeds missing fonts and optimizes them by forming subsets. Matching color profiles are created for device-dependent color spaces. An output intent is created where necessary. Prohibited content such as JavaScripts and unnecessary content is removed and required content completed where possible. The file is reformatted during conversion and safe repairs are carried out.

Digital signing: The application of an advanced electronic corporate signature or personal Qualified Electronic Signature (QES) guarantees the authenticity and integrity of archived documents. Embedding a time stamp and revocation information keeps the digital signature verifiable in the long-term.



Stay informed about the special format for electronic invoices


  • What is ZUGFeRD?
  • Where is ZUGFeRD used and when does it make sense?
  • What do you have to keep in mind?
  • How does PDF Tools AG support ZUGFeRD?