Compare PDF
Choose two versions of a PDF and see which paragraphs were added, removed or left unchanged.
Both PDFs are read inside this page and never uploaded. Only their text is compared - not images, colours or layout.
What this tool does
A PDF comparison tool shows what changed between two versions of a document. This one extracts the text of both PDFs, splits it into paragraphs, and shows the paragraphs that were removed, added or unchanged, colour-coded. It compares the words, not images or layout.
Reads the text layer of both PDFs, rebuilds paragraphs from the positions of the words, and compares the two lists.
Shows removed paragraphs in red, added ones in green and unchanged ones in grey, with counts and a copyable list of the differences.
How to use it
- Choose the original PDF in the first box.
- Choose the changed PDF in the second box.
- Wait while both are read - long documents take a moment.
- Check the counts, then scroll the list: red was removed, green was added.
- Press Copy differences to paste the changes elsewhere.
Why use this PDF comparison
Compares the text of two PDFs paragraph by paragraph and colours what was removed and what was added. When a contract, report or policy comes back with "minor updates", the only safe way to know what changed is to compare it. Doing it by eye across many pages is slow and misses small edits.
Why we built it
We built the compare PDF tool to compare two versions paragraph by paragraph and colour what was added and removed. For plain text use the text diff checker and extract the text first with PDF to text.
Related tools worth a look: the PDF to Word.
Who this tool is for
- Lawyers, editors and reviewers comparing versions
- Students checking changes
- Teams reviewing contracts
When to use it
- Checking a revised contract against the version you agreed.
- Seeing what changed between two drafts of a report.
- Verifying that a re-exported PDF still has the same text.
- Reviewing updated terms or policies.
How it works
Words are read from each PDF with their positions, grouped into lines by baseline, and lines into paragraphs by vertical spacing. The two lists of paragraphs are then compared with a longest-common-subsequence diff, the same method used by source-code comparison tools.
A paragraph that was edited shows as one removed paragraph and one added paragraph, so you see the old wording and the new wording together.
Only text is compared. A changed image, a different font or colour, or a re-flowed layout will not appear as a difference unless the words changed.
What you give it, and what you get back
| Item | Details |
|---|---|
| Input | Two PDFs with a text layer. |
| Output | A colour-coded list of removed, added and unchanged paragraphs. |
| Counts | Paragraphs removed, added and unchanged, and a verdict. |
| Copy | The removed and added paragraphs as plain text. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| "No readable text" message | One of the PDFs is a scan. | Use a text-based PDF; this tool does not read images of text. |
| Everything shows as changed | The documents were re-flowed, so paragraphs split differently. | Compare against the same layout or export. |
| Reports identical but looks different | Only images or colours changed. | This is a text comparison. |
| Very long documents are cut | The comparison covers the first 1,500 paragraphs. | Split the PDFs into parts and compare each. |
Assumptions and limitations
- Compares text only, not images, formatting or layout.
- Scanned PDFs without a text layer cannot be compared.
- Only the first 1,500 paragraphs of each file are compared.
- Paragraph boundaries are inferred, so re-flowed text can look different.
Frequently asked questions
How do I compare two PDF files?
Choose the original in the first box and the changed version in the second. The tool lists the paragraphs that were removed and added.
Does it compare images and formatting?
No. It compares the text only. A changed image, font or colour is not detected unless the words themselves changed.
Why does it say there is no readable text?
The PDF is probably a scan - a picture of each page - with no text layer to compare.
Are my PDFs uploaded to compare them?
No. Both files are read in your browser and nothing is sent to a server.
Why does an edited sentence appear twice?
A changed paragraph is shown as the old version (removed) and the new version (added) so you can see both side by side.