---
title: "Automatically tag PDFs for PDF/UA-1 compliance"
canonical_url: "https://www.nutrient.io/guides/document-engine/conversion/to-pdfua/"
md_url: "https://www.nutrient.io/guides/document-engine/conversion/to-pdfua.md"
last_updated: "2026-06-08T19:21:59.160Z"
description: "Learn how to automatically tag PDF documents for PDF/UA-1 accessibility compliance using Nutrient Document Engine build instructions."
---

# Convert PDFs to PDF/UA-1

Document Engine can automatically tag PDF files and target PDF/UA-1 output by using build instructions with `output.type` set to `pdfua`.

PDF/UA auto-tagging requires the PDF/UA accessibility auto-tagging feature in your Document Engine license.

- Ensure [Document Engine is up and running](https://www.nutrient.io/sdk/document-engine/getting-started.md).

- Send a [multipart POST request](https://www.baeldung.com/postman-form-data-raw-x-www-form-urlencoded) with [instructions](https://www.nutrient.io/api/reference/document-engine/upstream/#tag/Build-API) to Document Engine’s `/api/build` endpoint.

For more information, refer to the [API reference](https://www.nutrient.io/api/reference/document-engine/upstream/#tag/Build-API) to learn about the `/api/build` endpoint and all the actions you can perform on PDFs with Document Engine.

For an overview of multipart requests, refer to the [brief tour of multipart requests](https://www.nutrient.io/blog/a-brief-tour-of-multipart-requests/) blog post.









## Convert a PDF file to PDF/UA-1

Send a multipart request to the [`/api/build` endpoint](https://www.nutrient.io/api/reference/document-engine/upstream/#tag/Document-Editing/operation/build-document), attaching the input PDF and the [`instructions` JSON](https://www.nutrient.io/api/reference/document-engine/upstream/#model/BuildInstructions).

The examples below use `localhost:5001`. If your host port mapping is different, adjust the URL accordingly.

### SHELL

```shell

curl -X POST http://localhost:5001/api/build \
  -H "Authorization: Token token=<API token>" \
  -F document=@/path/to/input.pdf \
  -F instructions='{
  "parts": [
    {
      "file": "document"
    }
  ],
  "output": {
    "type": "pdfua",
    "metadata": {
      "title": "Accessible annual report",
      "author": "Nutrient"
    }
  }
}' \
  -o output-pdfua.pdf

```

### HTTP

```http

POST /api/build HTTP/1.1
Content-Type: multipart/form-data; boundary=customboundary
Authorization: Token token=<API token>

--customboundary
Content-Disposition: form-data; name="document"; filename="input.pdf"
Content-Type: application/pdf

<PDF data>
--customboundary
Content-Disposition: form-data; name="instructions"
Content-Type: application/json

{
  "parts": [
    {
      "file": "document"
    }
  ],
  "output": {
    "type": "pdfua",
    "metadata": {
      "title": "Accessible annual report",
      "author": "Nutrient"
    }
  }
}
--customboundary--

```

## Apply PDF/UA auto-tagging to an existing Document Engine document

If your document is already stored in Document Engine, use [`/api/documents/{documentId}/apply_instructions`](https://www.nutrient.io/api/reference/document-engine/upstream/#tag/Document-Editing/operation/document-apply-instructions).

This replaces the document’s base layer with the processed (tagged) result.

```shell

curl -X POST "http://localhost:5001/api/documents/<documentId>/apply_instructions" \
  -H "Authorization: Token token=<API token>" \
  -H "Content-Type: application/json" \
  -d '{
  "parts": [
    {
      "document": {
        "id": "#self"

      }
    }
  ],
  "output": {
    "type": "pdfua"
  }
}'

```

## Notes and best practices

- `pdfua` output returns a PDF file (`application/pdf`).

- Auto-tagging reduces manual accessibility work, but you should still validate output in your QA process for high-stakes or regulated workflows and strict compliance requirements.

- You can combine `pdfua` with other PDF output options available in the base PDF output model (for example, metadata and optimization options).

- Some optional output settings may require additional licensed features in your Document Engine deployment.
---

## Related pages

- [Convert CAD files to PDF](/guides/document-engine/conversion/cad-to-pdf.md)
- [Convert HTML to PDF](/guides/document-engine/conversion/html-to-pdf.md)
- [Convert image files to PDF](/guides/document-engine/conversion/image-to-pdf.md)
- [PDF and document conversion server](/guides/document-engine/conversion.md)
- [Convert MS Office documents to image files](/guides/document-engine/conversion/office-to-image.md)
- [Convert PDF to HTML](/guides/document-engine/conversion/pdf-to-html.md)
- [PDF to Excel](/guides/document-engine/conversion/pdf-to-excel.md)
- [Convert Office files to PDF](/guides/document-engine/conversion/office-to-pdf.md)
- [Convert PDF to Office](/guides/document-engine/conversion/pdf-to-office.md)
- [Convert text files to PDF](/guides/document-engine/conversion/text-to-pdf.md)
- [Convert PDF to image](/guides/document-engine/conversion/pdf-to-image.md)
- [Easily convert documents to PDF/A formats](/guides/document-engine/conversion/to-pdfa.md)