Compare PDF renders matching pages from an original and modified document, then highlights differing pixels so you can review revisions without uploading either file.
InputTwo PDF files
OutputA side-by-side comparison view
RequirementsTwo readable PDF files are required. The comparison is visual and page-based; it does not create a new PDF.
Step-by-Step Instructions
Follow these essential instructions to achieve optimal results when using Compare PDF:
Open Compare PDF and choose the Original PDF file.
Choose the Modified PDF file and wait for both previews to load.
Select Compare Pages, then move through pages with the arrows.
Review the highlighted differences and page counts before acting on the result.
Interactive Tutorial
Visual Step-by-Step Walkthrough
Follow these real interface screenshots captured directly from Compare PDF. Every step highlights the exact buttons, selections, and downloads. Click any screenshot or "Launch Fullscreen Viewer" to inspect in high resolution.
Step 1 of 7 Dual Drop Zones (#drop1, #drop2)
Open Compare PDF
What to do:
Open Compare PDF to highlight visual differences, edits, and pixel shifts between two documents.
What you will see:
The workspace features dual upload zones: Original PDF on the left, Modified PDF on the right.
Next:
Load the baseline document into the first drop zone.
Tip:
Compare PDF is an on-screen visual auditor that runs 100% locally in your browser.
Step 2 of 7 Original File Browser (#fin1)
Upload Original Document
What to do:
Select the earlier or baseline PDF version into the first upload box.
What you will see:
The original document details and page count load into the left panel.
Next:
Proceed to select the revised document in the second box.
Tip:
Comparing matching drafts with identical page sizes produces the clearest visual diff.
Step 3 of 7 Modified File Browser (#fin2)
Upload Modified Document
What to do:
Select the updated or modified PDF version into the right upload box.
What you will see:
The modified document loads into the right panel with its page count.
Next:
Inspect both side-by-side previews.
Tip:
Both files must be readable PDFs.
Step 4 of 7 Preview Panes (.preview-wrap)
Review Side-by-Side Previews
What to do:
Confirm that both documents are aligned to corresponding sections.
What you will see:
Side-by-side previews show page 1 of each document.
Next:
Focus on the "Compare Pages" action button.
Tip:
Verify page counts to see if any pages were added or removed in the revision.
Step 5 of 7 Compare Action Button (#goBtn)
Click Compare Pages
What to do:
Click the primary "Compare Pages" button.
What you will see:
The visual diff engine rasterizes matching pages and runs pixel-by-pixel differential analysis.
Next:
Observe the highlighted changes on the comparison canvas.
Tip:
All pixel analysis executes directly in WebAssembly inside your browser.
Step 6 of 7 Diff Viewer (#diffViewer)
Audit Highlighted Differences
What to do:
Inspect the highlighted color-coded difference overlays.
What you will see:
Modified text, changed numbers, and shifted images are highlighted with vibrant diff colors.
Next:
Review the flagged differences to verify contract changes.
Tip:
Unchanged content remains neutral, allowing edits to stand out instantly.
Step 7 of 7 Page Navigation Buttons (changePage)
Navigate & Audit All Pages
What to do:
Use the left and right navigation arrows to audit differences across every page.
What you will see:
The comparison viewer shifts page by page, highlighting edits on each sheet.
Next:
Complete your audit of all revisions between the two versions.
Tip:
Compare PDF is an interactive inspection tool; your original files remain unmodified.
Tips & Best Practices
Use matching versions with similar page sizes for the clearest comparison.
Check more than the first page when a change may be later in the document.
Common Mistakes to Avoid
Selecting the same version twice hides meaningful changes.
Expecting a downloadable redline file; this tool provides an on-screen comparison.
Troubleshooting & FAQ
If a file will not load, confirm it is a readable PDF and try a fresh copy.
If pages have different sizes, compare the content visually rather than relying on pixel counts.