Compare PDF documents to see exactly what text changed between two versions, right in your browser. This pdf diff tool extracts the selectable text from an original (A) and a changed (B) file, then runs a line-by-line comparison and highlights every added and removed line with running counts. It is handy for reviewing contract revisions, spotting edits between report drafts, or confirming a regenerated export matches the previous one. Writers, QA engineers, legal teams, and developers who need to diff two PDFs without copy-pasting text by hand will find this pdf compare tool fast and accurate. Everything runs locally in your browser, so your documents never leave your device and nothing is uploaded to a server. Drop in two PDFs and the comparison updates instantly, with a clear message when the text is identical.
Features
Extracts selectable text from each PDF and diffs it line by line
Highlights added lines in green and removed lines in red
Shows running counts of added and removed lines at a glance
Reports clearly when both documents have identical text
Compares text content rather than visual layout or pixels
Pauses automatically on very large files (over 5,000 lines) to stay responsive
Runs entirely in your browser with no upload step
Lets you clear and swap either side to re-run the comparison
How to use the Compare PDFs
Drop or select the original PDF into the Original (A) slot.
Drop or select the revised file into the Changed (B) slot.
Wait a moment while the text is extracted from each PDF.
Review the line-by-line diff, with added and removed lines highlighted and counted.
Clear either slot to load a different file and compare again.
Example
Input
A: Invoice total: $1,200
Due on receipt
B: Invoice total: $1,450
Due on receipt
Output
- Invoice total: $1,200
+ Invoice total: $1,450
Due on receipt
+1 −1 lines
Diffing the text of two invoice PDFs
Common errors & troubleshooting
A scanned PDF shows no differences or empty output. — Scanned pages are images without selectable text. Run OCR first so the PDF contains real text, then compare.
The comparison is paused with a 'very large' warning. — One or both documents exceed 5,000 lines. Split or trim the PDFs into smaller sections and compare those parts.
Layout or font changes are not detected. — The tool diffs text content, not visual formatting. Use it to find wording changes, not styling or page-layout differences.
'Could not read PDF' error appears. — The file may be corrupted, encrypted, or not a valid PDF. Re-export or decrypt the document, then drop it in again.
Frequently asked questions
What is the Compare PDF tool?
It extracts the selectable text from two PDFs and runs a line-by-line diff, highlighting added and removed lines so you can see exactly what changed between versions.
How do I compare two PDF files?
Drop the original into the Original (A) slot and the revised file into the Changed (B) slot. The diff appears instantly once the text is extracted from both.
Does Compare PDF diff the visual layout?
No. It compares the extracted text content line by line, not pixels, fonts, or page formatting, so it finds wording changes rather than styling differences.
Can I compare scanned PDFs?
Only if they contain selectable text. Scanned image-only pages need OCR first, since there is no text to diff otherwise.
Is there a size limit when comparing PDFs?
Comparison pauses when a document exceeds 5,000 lines so the tool stays responsive. Break very large PDFs into smaller parts to compare them.
Are my PDFs uploaded anywhere when I compare them?
No. Both files are processed locally in your browser and your documents never leave your device.
Related tools
PDF to Text — Extract selectable text from a PDF as plain text or Markdown.
Merge PDFs — Combine multiple PDFs into one, with reordering.
Split PDF — Extract pages or ranges (e.g. 1-3,5,7-9) into a new PDF.
Organize PDF — Reorder, rotate and delete pages from thumbnails, then export.
Watermark PDF — Add a diagonal text watermark to every page.
Text Diff — Compare two texts line-by-line and see additions and removals.
Rotate PDF — Rotate all pages or a selection by 90/180/270°.
Crop PDF — Trim margins from every page via the crop box.