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Compare Two PDF Files

Put two versions of a document next to each other and see exactly what changed. Pages are paired in order, differences are listed line by line, and a side-by-side PDF lets you check the layout as well as the words.

Files are never uploaded

How to use it

Add both versions

Drop the original first and the revised copy second; the order decides which version is shown on which side. Two files are needed — with one, there is nothing to compare against.

Let the pages pair up

Page 1 is compared with page 1, page 2 with page 2, and so on. If one document is longer, the extra pages are reported as present on one side only.

Read the difference report

A text file lists every changed page: lines starting with "-" were removed, lines starting with "+" were added. Pages with no changes say so plainly.

Check the side-by-side PDF

The comparison PDF shows Original on the left and Revised on the right, so you can catch layout shifts, moved blocks and changed images that a text comparison alone would miss.

Download what you need

Keep both files, or just the one that answers your question. The originals on your computer are left untouched.

Common issues

The report is empty but the documents differ

Both files probably lack a text layer, or the change is purely visual — a moved image, a new logo, a shifted margin. Look at the side-by-side PDF, which compares the rendered pages rather than the words.

Nearly every page shows changes

This usually means a page was inserted or removed near the start, pushing every later page out of alignment. Compare the page counts in the report header before judging the differences.

"Removed" and "added" look backwards

The first file is treated as the original and the second as the revised copy. Added in the other order, the report reads in reverse — swap the files and run it again.

A long document is slow to render

Every page of both files is drawn to an image for the side-by-side view. Set image quality to Fast for a quicker run; the text report is produced either way.

Frequently asked questions

What exactly gets compared?
Two things: the text layer, line by line, and the rendered pages, shown side by side. The text report catches wording changes precisely; the side-by-side pages reveal anything visual.
How are pages matched up?
By position — page 1 against page 1. Inserting a page near the start therefore shifts everything after it and shows up as changes on many pages. That is the honest result of comparing page for page.
Do both files need the same number of pages?
No. When one document has more pages, the extra pages are reported as existing on one side only, and the side-by-side view leaves the missing side blank.
Why is a page marked as changed when it looks identical?
Small differences in the text layer count: a re-exported PDF can hold the same words with different spacing or line breaks, so lines no longer match exactly. The report shows which lines are involved.
Can it compare two scanned PDFs?
Not at the word level. Scans have no text layer, so the text report comes back empty, but the side-by-side pages still let you compare them by eye. Run OCR PDF on both first if you want a word-level comparison.
Does it show word-level changes?
No — the comparison is line by line. One corrected word marks the whole line as changed, which is usually what you want when reviewing a document rather than auditing character by character.
Are the original files modified?
Never. Both source files are only read. Nothing is written back to them, and nothing is sent to a server.
What if I add the files the wrong way round?
The report still shows the differences, but "removed" and "added" will be reversed. Check the file names at the top of the report; if they are swapped, run it again with the files the other way round.
Is there a size limit?
No fixed limit. Both documents are rendered in your browser, so very long files use more memory. If a large pair feels slow, set image quality to Fast to reduce the rendering work.

Related tools

Merge PDFCombine several PDFs into a single document in the order you choose. Everything runs inside your browser. Split PDFPull out the pages you need, or break one document into several. Type the ranges and each one becomes its own downloadable PDF. PDF to TextGet the words out of a PDF as plain text, page by page, without copy and paste. Handy for quoting, searching or scripting. Extract PDF PagesTake only the pages you need and leave the rest behind. List the numbers and get one new PDF containing exactly those sheets.

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About this page. Written and maintained by the AI-Mind team. Last reviewed 11 October 2026. This tool runs entirely in your browser. Found an error or have a suggestion? Use the feedback form above or email [email protected].