Edit PDF Bookmarks & Auto-Generate Table of Contents
Edit bookmarks, auto-create them or add a TOC page
Edit bookmarks, auto-create them or add a TOC page
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Add, rename, nest and relink PDF bookmarks (table of contents)
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About Edit PDF Bookmarks & Auto-Generate Table of Contents
PDF bookmarks, called the document outline in the specification, are the table of contents that appears in a viewer's side panel. Unlike a printed contents page, the outline is a separate tree stored in the file's catalog, so renaming or reordering entries doesn't change a single character on the pages themselves.
There are three tabs. Edit lets you rework the existing bookmarks by hand. Auto-generate finds headings by font size and numbering patterns and turns them into bookmarks. Contents page reads the bookmarks and inserts a clickable table-of-contents page at the front of the document.
What the Edit tab writes to the file
On save, the old outline objects are deleted and a new tree is written from scratch. An entry can be indented at most one level deeper than the entry above it, and moving or deleting an entry carries its sub-entries along. When you delete an entry, its children aren't lost; they move up one level.
There are two jump styles. “Go to top of page (keep current zoom)” is stored as an XYZ destination pointing at the page's top-left corner with the zoom left empty; “Fit the whole page” is stored as a Fit destination. Existing bookmarks whose target page can't be resolved, such as ones pointing to external links, keep their names but are saved without a target, so relink them with the 🔗 button. Saving with an empty list removes the outline entirely.
Auto-generate and the contents page
Auto-generate first estimates the body text size, then proposes as headings any line that is at least a set ratio larger (115% by default), any line set in a font whose name marks it as bold, and any line that starts with a numbering pattern such as “Chapter 1”, “1.1”, “I.” or “A.”. Lines longer than 80 characters and headers, footers and page numbers that repeat on every page are skipped. A scanned PDF with no text layer gives no candidates; run OCR first.
The Contents page tab lays out up to three outline levels with indents, dot leaders and page numbers, and gives every line an internal link to its page. By default it prints the page numbers after insertion, so adding a two-page contents section after the cover shifts every body page number by two. Switch to “Original page numbers” if you want the source numbering shown instead.
Worked examples
Finding headings in a report automatically
- Input
Body text 10 pt, heading “1. Overview” at 14 pt, “1.1 Background” at 11 pt bold, threshold 115%- Output
“1. Overview” at level 1, “1.1 Background” at level 2
14 pt is 140% of 10 pt, so it passes the size test. 11 pt is only 110% and would miss on size alone, but it is bold and matches the “1.1” pattern, so it becomes a candidate one level down.
How to use it
- Add a PDF; its existing bookmarks appear in the list (or pick the Auto-generate or Contents page tab).
- Rename entries and use the arrows to change order and nesting, or adjust the candidates and settings.
- Save, then click entries in your viewer's bookmarks panel to check where each one lands.
Frequently asked questions
Why can't I see the bookmarks in Chrome?
In the built-in viewers of Chrome and Edge you have to open the outline from the side panel button. “Show bookmarks panel on open” writes PageMode UseOutlines into the file, and whether a viewer honors it varies.
Does editing bookmarks re-save the page content?
The file is saved again, but the page content streams are left as they are. Because the file is rewritten, any existing digital signature becomes invalid.
Will titles with accents or non-Latin scripts survive?
Yes. Bookmark titles are stored as UTF-16BE text. The Contents page tab embeds Noto Sans KR whenever a title contains characters outside printable ASCII so the page can draw them.
Notes
How the catalog and objects inside a PDF link together is covered in the guide “How PDF Files Work”.
Sources
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