The problem

You send a draft. It comes back clean: no tracked changes, or with Track Changes switched off part of the way through. You want to review their edits the normal way, in Word, accepting and rejecting one at a time and replying in the document. For that you need their version with the differences recorded as tracked changes.

How RedlineKit builds the tracked-changes file

RedlineKit compares the two versions word by word, then writes the result into a copy of the revised document. Every difference becomes a real tracked change, stored with the same markup Word itself uses when Track Changes is on:

Text that is in the revised version but not the original becomes a tracked insertion.
Text that was in the original but is gone from the revised version is put back in place as a tracked deletion, keeping the formatting it had in the original (bold, italics, size).
A whole paragraph that was added or removed has its paragraph mark tracked too, so accepting or rejecting it leaves no stray empty paragraph.
Unchanged paragraphs are copied byte for byte, so the document’s styles, list numbering, tables, images, headers and footers stay exactly as the revised file had them.

Accept every change and you have the revised document. Reject every change and you are back to the original’s text. That is the property RedlineKit’s test suite checks on every build, and we open the exports in LibreOffice Writer to confirm it lists each change as a tracked change.

Compare two files now Free on screen. Files stay on your device.

Step by step

Drop your version on Original and theirs on Revised, then press Compare.
Check the changes on screen. This part is free.
Set Changes by to the name you want shown in Word’s Review pane (for example the other party’s name, so the changes are attributed to them).
Press Word, tracked changes. One credit covers this pair, in both formats, as many times as you download it.
Open the file in your word processor and review with the usual Accept and Reject buttons on the Review tab.

When the revised version is a PDF

If the version you received is a PDF, there is no Word file to copy the layout from. RedlineKit builds a new, plain .docx from the compared text, with headings kept as headings and every difference tracked. It won’t look like the PDF, but every change is there to accept or reject, which is often the quickest way to get a signed or printed copy back into an editable draft.

Good to know

Moves are recorded as a deletion and an insertion in the Word file. On screen and in the PDF redline they are shown in green and linked to each other.
Formatting-only changes aren’t tracked. If they only made a heading bold, that difference isn’t marked.
Existing tracked changes in the revised file are kept as they were; the comparison treats them as accepted.
Headers, footers, footnotes and comments come across from the revised file unchanged and aren’t compared.

Why not just use Word’s Compare?

If you have desktop Word and both files are .docx, its Review › Compare › Compare Documents command does a similar job, and you should use whichever you prefer. RedlineKit is for when you’re not at a machine with desktop Word, when one version is a PDF, when you want to check the changes in a browser first, or when you also want a PDF redline to send round.

Turn two versions into tracked changes