Split PDF by Bookmarks
Split a PDF into one file per bookmark, named after each bookmark — perfect for chaptered ebooks, contracts and reports.
Quick answer: Drop a PDF with bookmarks and we read its outline tree with pdf.js, resolve each bookmark to a starting page, slice the file at those boundaries with pdf-lib and ship one PDF per section in a ZIP — bookmark titles become the file names.
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Frequently asked questions
- What if my PDF has no bookmarks?
- There's nothing for us to split on — the tool will tell you. Use the regular Split PDF tool to split by page range instead, or open the file in Acrobat / Foxit and add bookmarks first.
- How are output files named?
- Each file is named '<original>-NN-<bookmark title>.pdf', e.g. 'report-01-Executive Summary.pdf'. We sanitise illegal filename characters automatically.
- Can I split at sub-chapters too?
- Yes — uncheck 'Only top-level bookmarks'. Then every nested bookmark becomes its own file, indented in the preview list so you can see the hierarchy.
- What if two bookmarks point to the same page?
- They'll produce two single-page PDFs of that same page (one per bookmark). It's almost always a sign the source PDF has duplicate or stub bookmarks — review the preview before splitting.
- Are pages re-flowed or just sliced?
- Just sliced. Each section keeps the original layout, fonts and embedded images byte-for-byte; only the page selection changes.
- Is anything uploaded?
- No — pdf.js reads the outline, pdf-lib slices, JSZip packages, all in your browser. Network panel stays empty after the page loads.
- Can I split by chapter for a 500-page book?
- Yes — performance scales linearly with page count. 500 pages with 30 chapters typically completes in 5-10 seconds on a modern laptop.
- Will bookmarks be preserved in the output?
- No — once split, each section is its own document. The bookmarks inside that section disappear because they referred to absolute page numbers in the original file. Use Merge PDF to recombine if you change your mind.
- Does it work with encrypted PDFs?
- Only if the file is encrypted with an empty password (a flag-only encryption). Use Unlock PDF first if a real password is set.
- What's the difference vs. Split PDF?
- Split PDF asks for page ranges (e.g. '1-5, 6-10'). Split PDF by Bookmarks reads the bookmark tree automatically — no need to know where each section starts.