About Compare PDF
Compare PDF shows the text differences between two PDF files. Load the original and the changed version, click Compare, and read through a single view with added text in green and removed text in red with a strike-through.
Contract negotiations, policy updates and revised reports often arrive as a new PDF with no list of changes. Reading both versions side by side wastes time and misses small edits like a changed date, an added "not" or a different amount. This tool catches them in seconds.
Compare by words to see edits inside sentences, or by lines to get a quick overview of which passages changed.
How to use Compare PDF
- Drop the original PDF into the left box.
- Drop the changed PDF into the right box.
- Choose Words or Lines.
- Click Compare and read the highlighted result. The counters show how many words were added and removed.
Word-level precision
Spot single changed words, numbers and dates inside long paragraphs.
Summary counts
See at a glance how much text was added, removed and kept.
Confidential friendly
Both documents stay on your device. Ideal for contracts under negotiation.
Any PDF pair
Compare files from different software, as long as both contain real text.
Reading a comparison
The tool extracts the text of both PDFs, joins lines into paragraphs, and runs a difference algorithm that finds the longest stretches of matching text. Everything between matching stretches counts as a change: text present only in the new file shows as added, text present only in the old file shows as removed.
Word mode works best for edited documents where most text stays the same, such as contract revisions. It highlights each changed word, so you notice a figure that went from 30 days to 60 days. Line mode suits restructured documents where whole paragraphs moved or got rewritten, because word mode would produce a dense patchwork.
Layout changes don't count. If the new version uses a different font, moves a paragraph to the next page or changes margins, the comparison shows no difference as long as the words stay the same. Changes inside images and scanned pages stay invisible, because the tool compares text only.
PDFs from different sources sometimes split text differently, for example with hyphenation at line ends. The tool rejoins hyphenated words, but a few false differences can remain. Read the highlighted areas in context before you draw conclusions.
Tips for better results
- Use Words mode for contracts and Lines mode for rewritten documents.
- If one of the files is a scan, the comparison shows everything as removed or added. Both files need real text.
- Extract only the sections you care about with Extract PDF Pages to keep the result short.
- Save the comparison by printing the page to PDF from your browser.
Questions and answers
Does it compare images or formatting?
No. It compares text only. Changes to images, colors, fonts and layout don't show.
Can I compare scanned PDFs?
No. Scans contain images, not text. Both files need selectable text.
Are my documents uploaded?
No. Both files get processed in your browser.
Is there a size limit?
No fixed limit. Very long documents take longer to compare.
Why do I see differences in text that looks the same?
Invisible differences such as different hyphenation, spacing or special characters can show as changes.