Your scanner fed the document backwards — bottom page first, top page last. Now the PDF reads N to 1 instead of 1 to N. Reordering page by page would take an hour.
Reversal is one click. Flint supports it directly.
Select all, reverse, save
Open reorder PDF, drop the file, click 'select all', right-click 'reverse selection'. Every page flips position: page 1 becomes page N, page 2 becomes N-1, and so on. The grid updates instantly. Save.
Reverse a range only
Sometimes only part of the document needs reversing — pages 31-60 (the backs of a duplex scan) for example. Range-select 31-60, reverse just that selection. Pages 1-30 stay put; 31-60 flip. Save.
Print-stack reversal
Printer drivers sometimes need pages in reverse order so the output stack is right-side-up. If your printer does this, reverse the PDF before sending. Or look in printer settings for 'reverse order' or 'last page first' — many drivers have it built in.
Don't reverse if you don't need to
Most readers display pages 1 to N regardless of file order. A reversed file looks identical on screen if pages are labelled correctly. Reverse only when downstream systems (printers, archival) actually need the file order to match.
FAQ
Does this change the page labels?
Labels travel with their pages. If page 1 was labelled 'i' and now it's at position N, the indicator at position N shows 'i'.
Can I reverse without 'select all'?
Range-select any subset and reverse that. Selection is required to know what to reverse.
Does reverse affect bookmarks?
Bookmarks point at pages, which now occupy different positions. The bookmark still works; it just opens to its target page wherever it is.
Reverse a duplex flip case?
If only backs are reversed, range-reverse just the backs. Then if needed, re-interleave with fronts via split/merge.
One click, document flipped. Reverse page order.