Split a PDF by bookmarks
Automatically splits a PDF into multiple files, one per top-level bookmark in its built-in table of contents — handy for extracting each chapter of a book or each section of a report without typing page numbers by hand.
How it works
The tool reads the table of contents (bookmarks) built into the PDF and finds the page each top-level bookmark points to. Each section runs from its bookmark's page to the page before the next bookmark (or to the end of the document for the last bookmark), and becomes a separate, downloadable PDF file.
Why can't some PDFs be split this way?
Only PDFs exported with a navigable table of contents (from Word, LaTeX, InDesign, etc.) contain bookmarks. A plain scan or a "flat" export doesn't have any: in that case, the tool warns you rather than producing an arbitrary split.
Are only top-level bookmarks used?
Yes, to avoid over-fragmenting the document if the table of contents has several levels of subheadings. If you need a finer split, use the "Extract a page range" tool with the page numbers you want.
Reading the bookmarks and splitting the file both happen entirely in your browser (pdf.js for reading and WebAssembly for splitting) — your PDF never leaves your device.