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

  1. Add files by dropping them into the box, pasting, or clicking “browse”.
  2. Reorder by dragging the handle, or auto-sort by name, size, or date. Use Reverse to flip the current list.
  3. Optional per-file page ranges — click a file and enter something like 1-3,5,7- (see syntax below).
  4. Optional per-file reverse — click Reverse on a file to reverse just that file’s pages.
  5. Choose a merge mode: Sequential (file by file) or Interleave (round-robin: 1st page of each file, then 2nd, etc.).
  6. Use Rotate all if every page needs the same rotation (90° / 180° / 270°).
  7. Set Title and Author (optional) and choose an output filename.
  8. Click Merge now, then Download.

Page range syntax

  • 3 → only page 3
  • 1-3 → pages 1 through 3
  • 7- → page 7 to the end
  • 1-3,5,9- → 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.