When You Need to Compare PDFs
Comparing two versions of a PDF comes up more often than you might expect. Here are some common situations:
- Contract revisions. A client or lawyer sends back a "slightly edited" version of a contract. You need to know exactly what changed before you sign.
- Design proofs. A designer sends a revised layout. You want to see what moved, what changed color, or what text was updated.
- Document versions. You have two versions of a report and cannot remember which one has the latest corrections.
- Regulatory filings. You need to verify that a submitted document matches the approved version.
Scrolling back and forth between two PDFs in separate windows is tedious and error-prone. You will miss subtle changes — a swapped word, a shifted image, a removed paragraph. A dedicated comparison tool makes differences immediately visible.
Three Ways to Compare
PDFTaco offers three comparison modes, each useful in different situations:
Side by Side
Both PDFs are displayed next to each other, page by page. You can scroll through them in sync, looking at the same region of each document at the same time. This is the most intuitive mode and works well for most comparisons. It is especially good for text-heavy documents where you want to read both versions together.
Overlay Diff
The two PDFs are layered on top of each other. Pixels that are identical appear normally, while differences are highlighted in color. This mode makes even tiny changes — a period moved, a font changed, an image shifted by a few pixels — immediately obvious. It is the best choice for design proofs and visual documents where layout precision matters.
Slider
A draggable slider lets you reveal one version or the other. Slide left to see the original, slide right to see the revision. This is great for presentations and for quickly showing stakeholders what changed without needing to explain a diff view.
How to Compare PDFs with PDFTaco
- Open the Compare tool — Go to pdftaco.com/tools/compare.
- Upload both PDFs — Drop the original document and the revised version into the designated areas.
- Choose a comparison mode — Select side-by-side, overlay, or slider depending on what kind of differences you are looking for.
- Navigate page by page — Use the page controls to step through the document and examine each page.
- Spot the differences — Changes are immediately visible in whichever mode you choose.
Everything runs in your browser. Neither PDF is uploaded to a server, which matters when you are comparing confidential contracts, financial documents, or unreleased designs.
Tips for Spotting Differences
- Start with overlay mode for a quick scan. If you see highlighted areas, switch to side-by-side to read the actual text changes in context.
- Pay attention to small details. Check headers, footers, page numbers, and dates — these are common spots for subtle changes.
- Compare the right versions. Make sure you are loading the correct "before" and "after" files. Label your files clearly before starting.
- Check every page. Do not assume changes are limited to one section. Scroll through the entire document.
PDFTaco's compare tool is completely free, works in any browser, and keeps your documents private. The next time someone says "I just made a few small changes," you can verify exactly what those changes were.