Compare PDFs
Compare two PDFs side by side with text and pixel differences highlighted. Free, no signup — both files stay private in your browser.
PDF Compare shows you exactly what changed between two versions of a PDF — text differences, layout shifts, added or removed pages. Side-by-side preview with synchronized scrolling, color-coded line-level diff (green = added, red = removed, amber = modified), and pixel-level overlay for visual layout drift.
Text diffs, pixel diffs, and a per-page change heatmap in one view, with ignore-whitespace and ignore-case toggles so cosmetic edits do not bury real changes. No upload, no signup — both PDFs are rendered and compared in your browser via pdf.js and pdf-lib.
Features
- Side-by-side and overlay views — synchronized scroll keeps the same page visible in both versions
- Line-level text diff — LCS algorithm with intra-line word highlighting (red strikethrough for removed, green underline for added)
- Pixel-level visual diff — shows layout shifts, image changes, color differences with adjustable threshold
- Page-level summary — total pages added / removed / changed, percentage change per page
- Ignore whitespace + ignore case toggles — hide cosmetic-only differences for clean redline review
- Per-page heatmap — quickly find pages with the most changes
- Export diff report as PDF — sharable summary with thumbnails and change counts
- Browser-side — neither original nor revised PDF leaves your device
How to use Compare PDFs
- Open the original PDF (left side) and revised PDF (right side) — both render in parallel
- Heatmap shows per-page change density — click any page to dive into line-level diff
- Toggle "Ignore whitespace" and "Ignore case" to hide cosmetic-only differences
- Export the diff report as PDF for your records, or screenshot the side-by-side view for stakeholder review
Frequently asked questions
Is PDF Compare free?
Yes — text diff and pixel diff are both free with no signup. No file size limits beyond browser memory. Side-by-side preview, heatmap, and export are all included.
Does it work on scanned PDFs?
Pixel-level visual diff works on any PDF including scans. Text-level diff requires extractable text — for scanned PDFs, run OCR first (our OCR PDF tool), then compare the OCR'd versions.
Can I compare two versions of a contract?
Yes — that's the most common use. Turn on ignore-whitespace for the cleanest output. Export the diff report as PDF to share with the other side for redline negotiation.
Are my files secure?
Yes — both PDFs render and diff entirely in your browser via pdfjs-dist. Neither file is uploaded.
Can I compare PDFs of different page counts?
Yes — pages-only-in-A and pages-only-in-B are flagged in the heatmap. Aligned pages show line-level diff; orphan pages are previewed alongside.