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PDF Bookmarks Editor

Read, write or remove a PDF's outline. Free, and runs entirely in your browser — nothing you enter is uploaded, stored or sent to a server.

About PDF Bookmarks

Bookmarks are the outline a reader shows down the side of a long PDF, and they are the difference between a hundred-page document you can use and one you can only scroll. This reads them, writes them, and takes them away.

The format is deliberately plain text, because the thing people actually want is to edit the outline rather than to click through a tree: one bookmark a line, two spaces or a tab of indent for each level, then a tab and the page number. Read a document's outline, edit the text, write it back. It is also how an outline moves between two copies of a document — read from one, paste into the other.

A bookmark is stored as a doubly linked tree rather than a list, and a reader that finds a broken link in that chain shows nothing at all — which is why an outline written by hand in a hex editor so often disappears. Every entry written here gets its parent, its siblings and a destination that keeps the reader's zoom.

Where it helps

  • Reads the outline whichever of the three ways a PDF points at a page — direct, through an action, or by a named destination.
  • Round-trips: what it reads is exactly what it can write back.
  • Indentation makes the tree, so the nesting is obvious while editing.
  • Writes a properly linked outline — parents, siblings and destinations — rather than a list a reader will refuse.
  • The document stays in your browser.

Limits

  • The whole outline is replaced rather than edited in place: writing removes what was there.
  • Destinations are simplified to "the top of this page" — a bookmark that pointed at a spot partway down loses the exact position.
  • Styling that some producers add — a bold or coloured entry — is not preserved.
  • Open and closed states are not preserved; the tree comes back expanded.
  • Password-protected files must be unlocked first.

Frequently asked questions

What is the text format exactly?

One bookmark a line: the title, a tab, then the page number. Indent a line by two spaces or one tab to make it a child of the line above. Four spaces works too — the indentation is measured relative to the lines around it.

Why did my bookmarks disappear in the reader?

That is what a broken outline chain looks like. Every entry needs its parent and its neighbours to point at each other, and a reader that hits an inconsistency usually shows an empty panel rather than a partial tree. Writing the outline here rebuilds all of those links.

Can I keep the bookmarks when I merge documents?

The merge tool preserves them. This is for the cases where it cannot — documents that never had any, or an outline whose page numbers need shifting after an edit.

Do bookmarks affect the page numbers a reader shows?

No — that is what page labels are for. Bookmarks navigate; labels change what the page box says.

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