PDF Bookmark Editor

Add and edit bookmarks in a PDF

Bookmarks — the clickable outline in a PDF reader’s side panel — turn a long document into something people can actually navigate. The PDF Bookmark Editor shows the bookmarks a PDF already has, and lets you add new ones, rename them, link them to pages, nest them into chapters and sections, reorder them and delete them.

For reports, theses, manuals and e-books that have no bookmarks at all, the editor can create them automatically: it reads the text, finds lines set in a larger font than the body, ignores repeated headers and footers, and turns the biggest heading sizes into bookmark levels. You review the result, adjust anything, and save.

The file is edited in your browser and never uploaded. Page content stays exactly as it was — only the bookmark outline is rewritten.

How to use the PDF Bookmark Editor

1. Drop a PDF onto the upload area. Existing bookmarks appear as an indented list with their page numbers.
2. Edit a title or page number directly, or press “Add bookmark” to create a new entry at the end of the list.
3. Use the arrow buttons to move a bookmark up or down, and the indent buttons to nest it under the one above or move it up a level.
4. Optionally open “Auto-create from headings”, pick the sensitivity and number of levels, and press “Find headings”.
5. Choose whether the bookmarks panel should open automatically, then press “Save PDF with bookmarks”.

PDF Bookmark Editor features

How automatic bookmarks are detected

The editor reads every text line with the pdf.js engine and measures its font size. The most common size, weighted by the number of characters, is taken as the body text. Lines at least 20% larger (adjustable to 10% or 40%) become heading candidates; text that repeats on more than half of the pages is treated as a running header or footer and dropped. The largest heading size becomes level 1, the next level 2, and so on.

Each bookmark jumps to the top of its heading rather than just the top of the page. The method works best with documents exported from Word, Google Docs, LaTeX or InDesign. Scanned PDFs have no text layer, so add bookmarks manually or make the file searchable first.

Tips for good PDF bookmarks

• Keep titles short and specific — “3.2 Sampling method” is easier to scan than a full sentence.
• Mirror the document’s own structure: chapters at the top level, sections nested underneath.
• Two or three levels are usually enough; deeper trees are hard to use in a narrow side panel.
• After reordering pages with Organize PDF or combining files with Merge PDF, check that bookmarks still point to the right pages.
• Add page numbers with Add Page Numbers so printed copies stay navigable too.

Bookmarks, outlines and tables of contents

In the PDF specification bookmarks are called the document outline. They live outside the page content, so adding or removing them never changes how pages look or print. A table of contents printed on a page is different: it is part of the page itself and is not editable here. Many accessibility guidelines recommend bookmarks for any PDF longer than a few pages.