A contract goes out as a PDF, and a week later it comes back with a note: "a few small edits, nothing major". There is no track-changes history in a PDF, so the usual check is two windows side by side and a careful read, line by line. That works until the change is one digit in the payment terms, or a sentence that simply isn't there any more. Missing text is the hardest thing to spot by eye, because there is nothing on the page to catch your attention.
A text comparison catches both. The steps below use the PDF Editor in the osFoundry desktop app, which compares two versions of a PDF by their words rather than by how the pages look, marks every change on the version that came back, and writes a one-page summary. The example is a made-up design services agreement with six short clauses; the version that came back has five edits in it.
Open both versions
Open the PDF Editor and open both files: the version you sent first, then the one that came back. Each opens in its own tab.
Then go to All tools, click View more at the bottom of the list, and choose Compare files. In the Compare panel on the left, click Select files to compare.
The dialog asks which open file is the old one. Pick the version you sent; the file in front becomes the new one. The line under it describes the method: text is compared word by word, and the differences are shown on the new file. Because it reads the words in the PDF's text layer rather than comparing pictures of the pages, a single changed digit is listed just as plainly as a deleted paragraph.
Click Compare.
Read the list
The editor puts the two files side by side and lists the changes in the Inspector on the right, colour-coded by kind.
In the example the count reads 3 Replaced, 1 Inserted, 1 Deleted:
- "30" became "60": the client now has 60 days to pay instead of 30.
- "Late payments add a 2% fee each month." was deleted. Nothing on the new page shows where it used to be.
- "two" became "unlimited" rounds of revisions.
- "and all drafts" was inserted into the ownership clause.
- "the fee is paid in full." became "work begins.", so ownership moves when work starts, not when the designer is paid.
None of them is visible from a quick read of the new version on its own. The fifth one changes who owns the work in progress, and it is three words long.
There is also a Visual count next to the text changes. It counts places where the rendered pages look different, which happens around any edit that moves text. The text changes are the ones to read. Clicking an item in the list takes both pages to that spot.
Mark the changes on their version
Click New file only, so the view shows just the version that came back, then Mark as comments.
Each change becomes a highlight with a comment on the exact words, written as "Replaced: "30" with "60"" and so on. The deletion has nothing left to highlight, so it gets a comment marker where the sentence used to be. The editor confirms "Added 5 comments". Saving the file keeps them as ordinary PDF comments, which any PDF reader shows, so you can add your own questions next to them and send the file back.
Save a one-page report
Click Report... in the Inspector. The editor opens a new PDF, Compare Report, with both file names, the totals and every change with its old and new text.
Save it with the save button in the top bar. It is one page here, short enough to paste into an email or keep with the signed copy.
Before you sign
The comparison tells you what changed, not whether the change is acceptable. Some edits are routine; a payment term that doubles or ownership that moves to the start of the job usually deserves a question before anything is signed.
It only works on PDFs that have a text layer, which is the case for anything exported from Word, Google Docs or Pages. A scanned contract is a picture of text and needs text recognition first. The comparison runs inside the editor on your own computer, so neither version of the contract is uploaded anywhere, in line with osFoundry's local-first design. The desktop app is free from the osFoundry download page.
