Split PDF by Chapters Online Free
Automatically split a PDF into chapters using its built-in bookmark outline. Each top-level bookmark becomes a separate PDF file, packaged in a ZIP.
Detected Chapters
No Bookmarks Found
This PDF doesn't contain a bookmark outline or chapter structure. To split by chapters, the PDF must have bookmarks (also called outlines) that define chapter boundaries. Most ebooks, technical manuals, and well-structured documents include these. Try splitting by page ranges or individual pages instead.
Chapters ready
ZIP size: -
How to Split a PDF by Chapters Online
Use your PDF's built-in bookmarks to automatically split it into separate chapter files. No manual page counting, no guesswork — the tool reads the outline structure and splits accordingly.
- Upload your PDF — drag and drop a PDF that contains bookmarks (chapter outline).
- Review detected chapters — the tool scans the bookmark tree and shows which chapters it found, with page ranges for each.
- Click "Split by Chapters" — each chapter becomes a separate PDF file, packaged in a convenient ZIP download.
What Are PDF Bookmarks / Outlines?
PDF bookmarks (also called outlines) are the navigational table of contents embedded inside a PDF. You see them as the clickable sidebar in PDF readers like Adobe Acrobat, Preview, or your browser. They let you jump directly to chapters, sections, or figures. Well-structured PDFs — such as ebooks, technical manuals, academic papers, and reports — typically include bookmarks that map closely to the document's chapter structure.
When Is This Tool Useful?
- Ebooks and textbooks — extract individual chapters for easier reading or sharing.
- Technical documentation — split a large manual into manageable section PDFs.
- Legal documents — separate exhibits, appendices, or articles from a compiled filing.
- Academic theses — extract chapters for submission or review.
- Corporate reports — split annual reports or white papers by section.
What If My PDF Has No Bookmarks?
If no chapter bookmarks are detected, the tool will let you know. You can still split your PDF manually using our Split PDF tool, which lets you enter page ranges or split every page individually. To add bookmarks to a PDF, most PDF editors (including Adobe Acrobat and Preview) allow you to create an outline structure.
Privacy & Security
Your PDF never leaves your device. All outline detection and page splitting happens locally in your browser using pdf.js and pdf-lib. We do not upload, store, or analyze your files.
FAQ
Will my PDF file be uploaded to a server?
No. All processing happens in your browser using JavaScript. Your PDF never leaves your device. We cannot see or access your files.
How are chapters detected?
The tool reads your PDF's bookmark outline (the clickable table of contents in the sidebar). Top-level bookmarks and their immediate children that point to specific pages are used as chapter boundaries. Each bookmark starts a new chapter, which continues until the next bookmark's starting page.
What if my PDF doesn't have bookmarks?
The tool will display a message saying no bookmarks were found. You can use the Split PDF tool to manually enter page ranges, or add bookmarks to your PDF using a PDF editor before using this tool.
What format are the split files?
Each chapter is saved as a separate PDF file, and all chapters are packaged in a single ZIP file for easy download. The filenames are based on the chapter titles from the bookmarks.
Are nested bookmarks (sub-chapters) supported?
The tool processes all bookmark levels and sorts them by page number. Each bookmark that starts a new page range becomes a chapter boundary. Sub-chapters within the same page range are included in the parent chapter's PDF.
Can I choose which chapters to extract?
Currently the tool splits all detected chapters. If you need only specific chapters, you can download the ZIP and keep only the chapter PDFs you need, or use the Extract Pages tool for more control.
Does this work on mobile?
Yes, the tool works on mobile browsers. Chapter detection and splitting happen locally on your device. Large PDFs may be slower on mobile devices due to memory constraints.
What's the maximum file size?
Files up to 50 MB work reliably in most browsers. Larger files may be slow or exceed browser memory limits. The tool processes all chapters at once, so very large PDFs with many chapters may require more memory.