PDF Compare
PDF ToolsFind what actually changed between two versions of a document, down to the word.
Runs entirely in your browser — nothing is uploaded
Comparing two PDFs byte for byte is useless: re-exporting a document changes it without changing a single word, so a byte comparison always reports a difference and never tells you what it was. This reads the text out of both files and diffs that — matching lines first to find where the edits are, then comparing word by word inside the lines that moved, so an amended clause shows as the three words that changed rather than two whole paragraphs struck out and rewritten.
What people do next
Features
- Line-level matching with word-level detail inside changed lines.
- Additions, removals and edits distinguished by colour, icon and word — not colour alone.
- Changes-only view by default; unchanged text is one click away.
- Flags a differing page count, a resized page and a missing text layer.
- Copy a plain-text report of every difference.
- Both documents are read in your browser — neither is uploaded.
How to use the PDF Compare
- 1Drop the original into the left panel and the revised copy into the right.
- 2Press Compare and wait while both text layers are read.
- 3Read the summary first — pages differing, and lines added, removed and changed.
- 4Work down the differences; each changed line shows the old and new wording together.
- 5Copy the report if you need to send the changes to someone.
Frequently asked questions
Why not just compare the files directly?
Because two exports of an unchanged document are never byte-identical. Timestamps, object ordering and the producer string all shift, so a file comparison reports a difference on documents whose content is the same, and cannot tell you what changed when something genuinely did. Comparing the text answers the question people are actually asking.
Can it compare scanned PDFs?
No, and it says so rather than showing an empty diff. A scan is a picture of a page with no text layer, so there is nothing to read. Run it through the Image to Text tool first to get a text layer, or compare the two by eye. An empty result on a scan would be the most misleading answer this tool could give, which is why it is reported as an error instead.
What happens if a page was inserted?
Pages are compared by number, so inserting a page makes everything after it shift and show as changed. The tool warns you when the page counts differ. Read the first reported difference as the real edit and the rest as the knock-on effect — that is the honest limit of a page-numbered comparison.
Does it detect formatting changes?
No. It compares words, not appearance, so a change of font, colour, spacing or margins is invisible to it, and a paragraph moved to a different page with the same wording reads as unchanged. That is usually what you want when reviewing a contract; it is not what you want when reviewing a design.
Are differences in whitespace reported?
No. Runs of spaces and blank lines are normalised away before comparison, because a re-export routinely changes spacing without changing meaning. Reporting those would bury the real edits under noise.
How large a document can it handle?
Comfortably a normal contract or report. The comparison is quadratic in the number of lines on a page, so an extremely dense page hits a guard and is reported as wholly replaced rather than matched line by line — the tool tells you when that happens, and other pages are unaffected.