pdfcosmos

Edit PDF Bookmarks

Build a clickable table of contents for your PDF, all in your browser.

Free, fast, and privacy-first.

Add a PDF to edit its bookmarks

Its existing outline loads into the editor

or drag & drop a PDF here

PDF files only · one file at a time · up to 100 MB

Edit PDF bookmarks: build a clickable outline, privately

Give a PDF a proper table of contents: add bookmarks that jump to any page, rename them, reorder them, and nest them into sections. pdfcosmos reads and writes the outline entirely on your device, so the file is never uploaded.

The editor is a simple indented list (indent to nest, outdent to promote, move up/down to reorder), so it works with a mouse or entirely by keyboard. Applying writes a standards-compliant outline every PDF reader shows in its sidebar.

  • Nest into sections

    Indent/outdent to build multi-level outlines.

  • Keeps existing bookmarks

    Your current outline loads in so you can edit it.

  • Keyboard-accessible

    Every action has a button. No drag-only nesting.

  • Private by design

    Read and written in your browser. Nothing is uploaded.

How to edit PDF bookmarks

  1. Add your PDF

    Choose a PDF. Its existing bookmarks (if any) load into the editor.

  2. Build your outline

    Add bookmarks, set each one's title and page, and use indent/outdent to nest them.

  3. Apply & download

    Click “Apply bookmarks” to write the new outline into the PDF and download it, all in your browser.

Frequently asked questions

Are my PDF files uploaded to a server?
No. The bookmarks are read and written entirely in your browser (pdfjs + pdf-lib). Your file never leaves your device. You can confirm it in your browser's Network tab.
What are PDF bookmarks?
Bookmarks (the document outline) are the clickable table of contents shown in the sidebar of a PDF reader. Each one jumps to a page, and they can be nested into sections and subsections.
How do I create sub-bookmarks?
Use the indent (→) button on a bookmark to nest it under the one above it. Outdent (←) moves it back out. Move up/down reorders them. It's all keyboard-accessible.
Does it keep my existing bookmarks?
Yes. The current outline loads into the editor so you can tweak it. Applying replaces the outline with whatever is in the editor, so you're always in control.
Is Edit PDF Bookmarks free?
Yes, it's completely free to use, with no sign-up and nothing to install.