Compare PDF
Compare two PDFs and see what changed.
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About Compare PDF
Two versions of a contract rarely come with a change log. Add the original PDF and the changed one, and the tool pulls the text out of both, splits it into paragraph-sized lines and lines the two up, marking what was added and what was removed. Unchanged lines stay in view for context, along with page markers so you can find your place. It reads the words on the page only: layout, images and colors are not looked at.
Features
- Line-level comparison of the text extracted from both PDFs
- Totals for lines added and lines removed
- Unchanged lines and page markers kept for context
- Tells you whether the Original or the Changed file could not be read
- No download involved, so comparing needs no account
Limitations
- Only text is compared. Layout, fonts, images and colors are ignored, so a purely visual change shows no difference.
- A change inside a paragraph shows as the whole old line removed and the whole new line added; the exact words are not highlighted.
- Each file can be up to 50 MB and 4000 lines of extracted text; beyond that the tool asks you to compare shorter documents.
- A scanned PDF holds page images rather than text, so there is nothing for it to compare.
How it works
- Add the Original PDF in the first box and the Changed PDF in the second.
- Select Compare PDFs once both files are loaded.
- Read the totals of lines added and removed above the result.
- Scroll the result: added lines start with a plus sign, removed lines start with a minus sign and are struck through, and unchanged lines are muted.
- Select Reset to start again with a new pair of files.
Frequently asked questions
- No. It compares the text extracted from each file, so a moved image, a new color or a different font with identical words shows no difference. If the look of the page matters, look through the pages yourself as well.
- The comparison works on lines, and a line here is one reconstructed paragraph or heading. If any word in it differs, the old line appears as removed and the new one as added, so read the pair together to spot the edit.
- Each file's text is split by page, with a marker line before every page. They are compared like any other line, so if one version has extra pages, the extra markers show up as additions or removals.
- Both documents are held in memory as lines and matched against each other, so each is limited to 4000 lines of extracted text. For longer files, cut out the chapters you care about with the extract pages tool first.
- No. Both files are read by pdf.js in your browser and the comparison runs in the page. There is no download button on this tool, so a sign-in is not needed to use it.