Compare PDF files: what changed between two versions
PDF-Revision compares two versions of a PDF, such as contracts, offers, catalogues or drawings, and shows every change with its page and place in both versions. Text is compared as a sequence of words, drawings and scans pixel by pixel. The files are read in the browser and are not uploaded.
What is compared
- Text
- The words of both versions in reading order, also on pages with several columns and in tables. New line and page breaks, words hyphenated differently, ligatures, non-breaking spaces and typographic quotes are not changes.
- Inserted, deleted, changed
- Every place with the old and the new text. In short changes the affected characters are marked, so for CHF 12,500 to 13,500 only the digit.
- Moved
- A paragraph that went to another place appears once as moved, with both pages, and not as deleted and inserted again.
- Pages
- Inserted, removed and reordered pages are recognised by their text, pages without text by a small image of the page.
- Graphics
- Both pages are rendered and aligned, even when a drawing as a whole moved by a few millimetres. What remains is framed as a graphic change. The tolerance can be set.
- Scans
- Pages without a text layer are compared graphically only. There is no text recognition.
Views and export
- Side by side
- Both versions scroll together, aligned on the same text. Clicking a change shows it on the left and on the right.
- Overlay, swipe, blink
- The pages lie exactly on top of each other: only in the older version red, only in the newer version blue, the same grey.
- Text
- The whole text as a redline with struck and inserted passages, unchanged paragraphs folded away.
- Change report
- An A4 PDF with a summary, the list of all changes and small page views with numbered marks.
- Newer version with comments
- The newer PDF with real comments (highlights, carets, frames with the old text as a note), readable in PDF-XChange, Acrobat and other programs. The original pages stay as they are.
Example: a framework contract in two versions
The example in the tool, a three-page maintenance contract, gives exactly four changes:
| Changed, page 1 | CHF 12’500.00 → 13’500.00 |
|---|---|
| Inserted, page 1 | “Die Reaktionszeit beträgt vier Stunden.” |
| Deleted, page 2 | paragraph on consequential damage |
| Moved, page 1 → 2 | paragraph on spare parts, to the end of the contract |
| No change | paragraph set narrower, “Gewährleistungsfrist” hyphenated differently, page numbers |
In the plan example the whole drawing is shifted 3 mm to the right and 2 mm down. The tool aligns it and reports only the moved wall and the dimension 3.40 → 3.60.
Frequent questions about comparing PDF files
Are the PDF files uploaded?
No. Both files are read and compared in the browser, and the reports are made there too. Nothing is sent to Brevity or to anyone else.
Why does reflowed text not show as a change?
The tool compares the sequence of words, not the lines. A paragraph set in another width, other hyphenation or text that slides to the next page therefore gives no change.
Are drawings compared graphically too?
Yes. Every page is rendered, the newer version is aligned on the older one and the differences are framed. Dimensions and labels are also compared as text.
What about scanned documents?
Pages without a text layer are compared graphically and marked as such. Small shifts and dust on the scan are evened out.
How do I pass the result on?
As a change report in PDF, or as the newer version with comments that reviewers can go through in their PDF program.
Are there limits?
Documents with several hundred pages and 50 MB run in the browser. Encrypted PDF files can be compared but not commented. Text inside images is not recognised.