How do I count page numbers?

Use the physical page number (1-based). If the cover is page 1 and the body starts on page 2, write `[2]` for body chapter 1. Not the printed page label (i, ii, iii) — match what the PDF viewer shows in the page counter.

How deep can the tree go?

1–6 levels (`#` to `######`). The PDF spec allows deeper trees but six levels keeps things readable. Skipping levels (e.g. `#` then `###`) works but may look odd in viewers.

What happens to existing bookmarks?

They are removed. This tool clears `/Outlines` before writing the new tree. Back up the original PDF if you need to preserve the old outline.

Will viewers other than Acrobat show the bookmarks?

Yes. We use the standard PDF outline spec, so Acrobat, Preview, Chrome, Firefox, Edge, iBooks, etc. all display them identically. No Acrobat-specific actions are used.

Can it handle encrypted PDFs?

No. Unlock the PDF first, then run it through this tool.

Is anything uploaded?

No. pdf-lib runs entirely in your browser; the PDF stays local.

Back to PDF

PDF bookmarks — add an outline / bookmark tree

Add a PDF outline (bookmark tree) in one shot using a Markdown-like syntax (`# Chapter 1 [3]`). Built with pdf-lib's low-level Catalog → Outlines API. `#` count = nesting level (1–6), each line ends with the target page in `[3]` brackets. Perfect for scanned PDFs or long documents without chapter titles, so you can jump to sections in Acrobat / Preview / browser PDF viewers. Runs entirely in your browser — no upload.

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How to use

Drop or pick a single PDF. Write your bookmark tree in Markdown-like syntax. `#` count (1–6) is the nesting level, end each line with `[3]` to point to a page. Check the parsed outline preview for the hierarchy and count. Invalid lines are highlighted in red. Click Add bookmarks to bake the outline into a new PDF via pdf-lib.

FAQ

How do I count page numbers?: Use the physical page number (1-based). If the cover is page 1 and the body starts on page 2, write `[2]` for body chapter 1. Not the printed page label (i, ii, iii) — match what the PDF viewer shows in the page counter.
How deep can the tree go?: 1–6 levels (`#` to `######`). The PDF spec allows deeper trees but six levels keeps things readable. Skipping levels (e.g. `#` then `###`) works but may look odd in viewers.
What happens to existing bookmarks?: They are removed. This tool clears `/Outlines` before writing the new tree. Back up the original PDF if you need to preserve the old outline.
Will viewers other than Acrobat show the bookmarks?: Yes. We use the standard PDF outline spec, so Acrobat, Preview, Chrome, Firefox, Edge, iBooks, etc. all display them identically. No Acrobat-specific actions are used.
Can it handle encrypted PDFs?: No. Unlock the PDF first, then run it through this tool.
Is anything uploaded?: No. pdf-lib runs entirely in your browser; the PDF stays local.

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