So you can edit it and put it back with Add Bookmarks.

It says no bookmarks. Why?

Many PDFs have none, and merging usually discards them.

Does it show nested sections?

It lists the top level and how many entries sit inside each.

inspect

View PDF Bookmarks

See a document's outline, and export it to edit and put back.

Runs in your browser

How it works

Lists the outline a reader shows in its sidebar and exports it as JSON in exactly the format Add Bookmarks accepts — so reading an outline, editing it in a text editor and writing it back is a round trip that works without anyone reformatting anything.

Related tools

Add Bookmarks

/add-bookmarks-to-pdf

Remove PDF Bookmarks

/remove-pdf-bookmarks

Add Table of Contents

/add-table-of-contents-to-pdf

Questions

Why export as JSON?: So you can edit it and put it back with Add Bookmarks.
It says no bookmarks. Why?: Many PDFs have none, and merging usually discards them.
Does it show nested sections?: It lists the top level and how many entries sit inside each.