Merge PDF files — private, fast, and pixel-perfect
This tool combines multiple PDF documents directly in your browser — nothing is uploaded to a server. It uses pdf.js (for previews) and pdf-lib (for the actual merge), so pages are copied losslessly without rasterizing or reducing quality.
How to merge PDFs
- Add files by dropping them into the box, pasting, or clicking “browse”.
- Reorder by dragging the handle, or auto-sort by name, size, or date. Use Reverse to flip the current list.
- Optional per-file page ranges — click a file and enter something like
1-3,5,7-
(see syntax below). - Optional per-file reverse — click Reverse on a file to reverse just that file’s pages.
- Choose a merge mode: Sequential (file by file) or Interleave (round-robin: 1st page of each file, then 2nd, etc.).
- Use Rotate all if every page needs the same rotation (90° / 180° / 270°).
- Set Title and Author (optional) and choose an output filename.
- Click Merge now, then Download.
Page range syntax
3
→ only page 31-3
→ pages 1 through 37-
→ page 7 to the end1-3,5,9-
→ combine segments; the order within each file follows the range you specify
Tip: Use the per-file Reverse toggle to invert a file’s page order after applying the range.
Interleave mode
Interleave outputs pages in round-robin order across files: page 1 of each file, then page 2 of each file, and so on. This is handy for duplex scans or alternating front/back sets.
Rotate, metadata & filename
- Rotate all applies the same rotation to every page in the final PDF.
- Title / Author are embedded into the PDF’s document info (optional).
- Output filename is sanitized to a safe
.pdf
name.
Preview & quality
Thumbnails and the large preview are raster images rendered for speed; the final merged output is lossless because pages are copied at the PDF object level (images, vectors, fonts remain intact).
Privacy & security
- 100% client-side: files never leave your device.
- Works offline after load (browser cache permitting).
- No tracking pixels in the merge process; previews are generated locally.
Browser support & limits
- Modern Chromium, Firefox, Safari, and Edge are supported.
- Very large PDFs can be memory-intensive. If you hit a limit, try merging in batches, closing other tabs, or using a desktop device.
Troubleshooting
“No PDF header found”: The file isn’t a real PDF (or it’s corrupted/truncated). Re-download it, ensure it ends with .pdf
, and try again.
Password-protected file: Encrypted PDFs aren’t supported for merging here. Open and export them as unprotected PDFs first.
Preview failed but merge works: Some PDFs preview poorly yet still merge fine. Try merging anyway.
ArrayBuffer / memory errors: Add the file again, keep the tab active, and disable “memory saver” modes if enabled. For extremely large jobs, merge in smaller batches.
Keyboard & accessibility tips
- Use the file controls to reorder without drag-and-drop if preferred.
- Every control is reachable with the keyboard; status text updates live as you add or merge files.