Duplex Collate

A PDF produced by feeding a stack through a single-sided scanner twice, once for the fronts and once for the backs, which gives one file with all front pages first and all back pages after. The tool interleaves the two blocks into front 1, back 1, front 2, back 2 order. If the fronts and backs are in two separate PDFs, use Alternate & Mix Pages instead.

The split is the last page of the front block, which for a normal two-pass scan is exactly half the total. Click Auto-detect split (half) to fill that in, then read the preview summary, which shows the size of each block and the resulting page count before you commit.

If the stack held several short documents, such as two-page forms, enter the pages per document and the collated output is cut into chunks of that length. Multiple chunks download as a ZIP with one PDF per document; a single chunk downloads as a plain PDF.

A single collated file downloads under your original name with _collated added, for example scan_collated.pdf. Grouped output is a ZIP named scan_collated_grouped.zip containing the separate PDFs.

The page shows a summary line as you change the split point and back order, including the front and back block sizes and the output page count, and it warns when the blocks are uneven. There is no thumbnail preview, so check the first few pages of the download and switch the back block order if the backs come out reversed.

The output is rebuilt page by page, so page content and rotation are preserved but document-level bookmarks aren't carried across. Scanner output rarely has any, but if yours does you can add them again with Edit Bookmarks.

No. The PDF is opened in your browser, the pages are copied into a new document on your device, and the result is downloaded directly, so scans of forms and records never leave your computer.