Compare PDF
Compare two PDFs and get a unified text diff — see exactly what changed between versions.
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About Compare PDF
Two versions of a contract. A draft and a final. The same document two months apart. Compare PDF extracts the text from both files and produces a standard unified diff — the same format git diff uses — so you can scan changes line-by-line.
We compare text content, not layout. For visual diffs (cell shading, image changes), pair this with PDF to JPG and a visual diff tool.
How Compare PDF works
Three steps. Done in seconds.
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1
Upload two PDFs
Order matters: first = old, second = new.
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2
We extract text and diff
Both files are text-extracted via pdfminer, then run through Python's difflib for a standard unified diff.
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3
Download the diff
Plain-text diff file. Lines starting with - are removed, + are added, neither = unchanged.
Why Compare PDF on Pixenith
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Most jobs finish in under 5 seconds. Heavy ones run on dedicated worker pools.
Production engine
Powered by pikepdf, Ghostscript, Tesseract OCR, ONNX models — the same tech the pros use.
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Related PDF tools
Often used alongside Compare PDF.
- Merge PDF Combine multiple PDFs into a single document in the order you choose.
- Edit PDF Overlay text or images onto pages (front-end editor sends a list of operations).
- Redact PDF Cover text matching a regex pattern with opaque rectangles.
- Add watermark Stamp a text watermark across every page.
- OCR PDF Add a searchable text layer to scanned PDFs (Tesseract).
- AI Summarizer AI Summarize a PDF with AI.
Compare PDF — frequently asked questions
Everything you need to know.
Will the diff catch layout / image changes?
No — this is a text diff only. For visual changes, render both PDFs to images with PDF to JPG and compare visually.
What if both PDFs are scans?
Run OCR PDF on both first to extract text. Without text, there's nothing to diff.
How accurate is the diff on tables?
Tables are extracted as text rows, so row-level differences show clearly. Heavily merged-cell tables may have noisy diffs as text extraction can vary slightly between versions.
Why is the output a .txt and not a PDF?
Unified diff is a universal text format readable in any editor or diff tool. PDFs of diffs are visually pretty but harder to grep / pipe.
Can I diff three or more PDFs?
Not in one call — run pairwise diffs.