Did the new contract draft add pages you never saw? The PDF Difference Highlighter takes an original file and a revised file. It returns the revised file with a small label stamped on each page.
This tool checks page counts only. It does not read the words, images, or layout, so it cannot find edits inside a page. Use it as a quick page-level flag, not a full comparison.
Table of Contents
- What the Tool Does
- How to Use It, Step by Step
- How It Works
- Walkthrough With Two Contract Drafts
- What the Tool Cannot Do
- Limitations and Assumptions
- FAQs About the PDF Difference Highlighter
What the Tool Does
The tool has two upload boxes and one action button. Each part has a clear job.
- Original PDF: the older file. Its name appears under the box once chosen. Until then it reads "No file chosen".
- Revised PDF: the newer file. This is the file whose pages end up in your download.
- Tag Pages & Download: builds the stamped file and saves it as pdf-difference-highlighted.pdf.
A status line starts at "Choose both files to tag pages". It changes to "Ready to tag pages." when both files are loaded. You can also drop a PDF on either box.
How to Use It, Step by Step
- Click the Original PDF box and pick the older file.
- Click the Revised PDF box and pick the newer file.
- Wait for the status line to read "Ready to tag pages."
- Press Tag Pages & Download.
- Read the note under the boxes. Then open the saved file and check the labels at the top of each page.
The button is active from the start. With a file missing, it shows "Please choose both the Original PDF and the Revised PDF first." The order matters, so check each box.
How It Works
The tool loads both files and creates a new empty PDF. It then walks through every page of the revised file. For each page, it copies the page and stamps a label on it.
Upload Original and Revised PDFs→Compare Page Counts→Stamp a Label on Each Revised Page→Download Stamped PDF
Revised pages up to the original page count get a small blue label reading "Page N of revised file". Pages beyond that count get a red bar. It reads "Page N is beyond the original page count (M)", where M is the original total.
The original file is used only to learn its page count. None of its page content appears in the output.
Walkthrough With Two Contract Drafts
Marcus Lee holds draft one of a vendor contract with 8 pages. His lawyer sends draft two with 10 pages. He wants to know which pages are new.
He picks the older draft as Original PDF and the newer draft as Revised PDF. The status changes to "Ready to tag pages." He presses the button and the browser saves the file.
| Pages | Label Added | Color |
|---|
| 1 to 8 | Page N of revised file | Blue |
| 9 and 10 | Page 9 is beyond the original page count (8) | Red |
On screen, a note reads "The revised file has 2 more pages than the original (10 vs 8). The extra pages are marked with a red bar. Page content was not compared." The status reads "Done. Page labels added and your download has started."
Marcus now knows pages 9 and 10 are beyond the old count. The blue label on pages 1 to 8 does not mean those pages changed.
What the Tool Cannot Do
The blue label appears even when page 3 is word for word identical in both drafts. It also appears when page 3 has changed text. The tool treats both cases the same way.
It cannot show deleted pages inside the PDF, because they do not exist in the revised file. The on-screen note lists the missing page numbers instead. It also does not reorder or match moved pages.
For real text differences, extract the words first with PDF to Text. Then compare the two text files in a diff tool. The Compare Two PDFs tool covers the same job. To confirm page totals before you start, use the PDF Page Counter.
To mark up the stamped file by hand, open it in Annotate PDF. To read both drafts side by side, try the Online PDF Viewer. For word counts per version, see PDF Text Statistics. Related file tools live in the PDF tools hub.
Limitations and Assumptions
- Only page counts are compared, by position. Page 4 in one file is treated as page 4 in the other.
- The labels sit in the top left and cover a small strip of the page. The blue label is 150 points wide, and its text shrinks to fit narrow pages. The red bar runs almost the full page width.
- Labels ignore page rotation and may cover a line of text.
- Nothing in the original file appears in the result. Keep your original saved.
- A non-PDF file shows "Please choose a PDF file." An encrypted or damaged file shows "One of these PDFs could not be processed. It may be encrypted, password-protected, or corrupted." Nothing downloads in that case.
- Large files take longer, because the browser must hold both in memory.
- The tool keeps no copy of either file. Load them again after a page reload.
FAQs About the PDF Difference Highlighter
Does this tool find changed words or images?
No. It does not read page content at all. It only compares how many pages each file has and stamps labels on the revised pages.
Is my PDF uploaded to a server?
No. The code reads both files in your browser and builds the new PDF there. The page loads the pdf-lib library from a public code host, but your files are not sent anywhere.
What does the blue label mean?
It says "Page N of revised file". It marks any revised page within the original page count. It does not prove the page changed.
What happens if the original has more pages?
The output still contains only the revised pages. A note on screen names the missing original pages. One example reads "Pages 2 to 3 of the original are missing in the revised file."
Which file ends up in the download?
The revised file. Its pages are copied into a new document, and the labels are drawn on top.
Do the labels remove or hide my content?
No. The labels are drawn over a small strip at the top of each page. The rest of the page stays as it was, though the strip may cover a line of text.
This tool runs in your web browser and may not handle every PDF file, font, or browser the same way. Keep a backup of your original file. Reviewed for general accuracy by Prof. Dr. Khalil Mudassar, PhD.