PDF Compare
Compare two PDFs side-by-side — page count, per-page text diffs (Levenshtein similarity), metadata differences, structure (page sizes & fonts), image counts. 18+ extra features: 4 comparison modes, unified-diff / HTML / CSV / JSON renderers, significant-change finder, history & shareable URL. 100% client-side — no uploads.
About PDF Compare
Compare two PDFs side-by-side — page count, per-page text diffs (Levenshtein similarity), metadata differences, structure (page sizes & fonts), image counts. 18+ extra features: 4 comparison modes, unified-diff / HTML / CSV / JSON renderers, significant-change finder, history & shareable URL. 100% client-side — no uploads. Everything runs locally in your browser — your data never leaves your device.
How to use
- Enter your input in the tool above.
- Adjust any options to your preference.
- Use the Copy or Download buttons to save the result.
- Everything happens locally — your data never leaves your browser.
FAQ
Is my data sent anywhere?
No. PDF comparison runs 100% in your browser using JavaScript and pdf-lib. Your files never leave your device, and the tool works offline once the page is loaded.
What does PDF Compare detect?
It compares page counts, per-page text content (line-by-line diff with a Levenshtein similarity score), metadata fields (title, author, subject, keywords, creator, producer, dates), structure (page sizes, embedded font names), and per-page image counts. Choose from 4 comparison modes: text-only, metadata-only, full, or structure.
What extra features?
18 extras: page-range parser; text comparator (line-by-line diff); whitespace + case normalizers; metadata comparator; structure comparator (page count, sizes, fonts); unified-diff formatter; Levenshtein similarity score; page-by-page diff generator; diff statistics (added / removed / modified / unchanged lines); 4 multi-format renderers (text, HTML, CSV, JSON); copy + download; localStorage history (max 20); shareable URL; summary stats; page-count diff; metadata diff; font-usage diff; image-count diff; and a significant-changes finder that surfaces the pages with the most differences.
How is the similarity percentage calculated?
Per page, the tool computes a Levenshtein edit distance between the two text layers (after optional whitespace / case normalization), then converts it to a 0–100% similarity score: 100 means identical, 0 means completely different. The overall document similarity is the average of all compared pages.
Can I compare scanned PDFs?
Text comparison works on PDFs that contain an embedded text layer. Scanned PDFs without a text layer will report empty text on each page — structure and metadata comparisons still work. For true text comparison of scans, run an OCR pass first (see our PDF OCR Text Extractor) and then compare the OCR'd text.
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