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PDF Accessibility

PDF Tag Inspector

See the structure tree that assistive technology actually reads.

Processed locally in your browser. Your file is not uploaded to any server. How this works

  1. 01Add your file
  2. 02PDF Tag Inspector
  3. 03Download

Runs in your browser · nothing uploaded

About PDF tag inspector

This tool shows you the tree itself rather than a verdict about it. A tagged PDF carries a StructTreeRoot whose children are structure elements — `H1`, `P`, `Figure`, `Table`, `TR`, `TD`, `L`, `LI`, `Link` — arranged in a hierarchy that mirrors the document’s logical organisation, with each element pointing at the actual marked content on the page it describes. Reading that tree is the most direct way to understand what a screen reader will encounter. Several important problems are only visible here. Content can exist on the page but sit outside the tree entirely, in which case assistive technology never reaches it — a caption or a sidebar that a sighted reader sees and a screen reader user simply never hears. Elements can be tagged with the wrong type, such as a real data table built as a sequence of paragraphs, which destroys row and column navigation. And content marked as an artifact is skipped by design, which is correct for a running header and wrong for a footnote.

How to PDF tag inspector

  1. 01

    Open the PDF

    Drop in the document whose structure you want to examine.

  2. 02

    Read the tree

    Expand the hierarchy from the root. The nesting shown is the nesting a screen reader traverses.

  3. 03

    Look for content outside the tree

    Anything reported as untagged is invisible to assistive technology even though it renders on the page.

  4. 04

    Check element types

    Confirm tables are tagged as tables and lists as lists, rather than as runs of paragraphs.

What this tool does

  • Full StructTreeRoot hierarchy with every structure element type shown in place
  • Flags page content that sits outside the tree and is therefore never announced
  • Distinguishes real artifacts from content merely left untagged
  • Depth limit for keeping deeply nested table structures readable
  • Counts of each element type, for a quick sense of how the document was authored

Limitations worth knowing

Every PDF tool has constraints. Stating them plainly is more useful than discovering them halfway through your work.

  • This displays the tree; it does not judge whether the structure is semantically correct. Only a person can say whether a Figure should have been a Table.
  • It is not a PDF/UA validator and issues no conformance verdict.
  • Custom role-mapped element types appear under their custom names, which can obscure what standard type they map to.
  • A very large tagged document produces a long tree that takes patience to review, even with the depth limit.

How your file is handled

This tool runs entirely inside this browser tab. When you choose a file, your browser reads it from your own disk and hands the bytes to JavaScript running on this page — no network request carries your document anywhere. You can confirm that yourself: open your browser’s developer tools, switch to the Network panel, and run the tool. You will see no upload.

Nothing is stored after the fact. Closing or reloading this tab discards the file, the result and everything derived from them, because none of it ever left your machine. Read how local processing works.

Questions about PDF tag inspector

What is the tag tree?

A hierarchy stored under StructTreeRoot that describes the document logically — headings, paragraphs, tables, figures, lists — and points each element at the content it covers on the page. It is what assistive technology reads instead of the visual page.

What does it mean if content is outside the tree?

That a screen reader will never announce it. The text renders and a sighted reader sees it, but because no structure element references it, it is not part of the document as assistive technology understands it.

Should I turn on artifacts?

Turn them on when you suspect real content was wrongly marked decorative. Artifacts are skipped by design, which is right for running headers and page rules, and wrong for a footnote or a caption.

Can I edit the tags here?

No. This is an inspector. Fixing structure means re-exporting from the source document with proper tagging, or editing the tree in a dedicated PDF authoring tool.

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