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PDF comparison (also called PDF diff or document redlining) is the process of analysing two versions of a PDF and highlighting every difference — added text, deleted text, moved content, and changed images — in a side-by-side or overlay view. Upload two PDF files and see exactly what changed between them. Additions, deletions, and modified text are highlighted side by side. Free PDF comparison tool — no signup, no watermark, runs entirely in your browser.
PDF comparison (also called PDF diff or document redlining) is the process of analysing two versions of a PDF and highlighting every difference — added text, deleted text, moved content, and changed images — in a side-by-side or overlay view. Upload two PDF files and see exactly what changed between them. Additions, deletions, and modified text are highlighted side by side. Free PDF comparison tool — no signup, no watermark, runs entirely in your browser.
Comparing PDF files manually — reading two versions of a document side by side and noting every change — is time-consuming and error-prone for anything longer than a few pages. A PDF comparison tool finds every difference automatically in seconds. Contract and legal document review — when a counterparty returns a revised contract, a comparison tool immediately shows every clause that changed, every word that was added or deleted, and every number that was altered. Reviewing a 50-page contract for changes takes seconds instead of hours. Document version control — teams iterating on reports, proposals, and specifications often produce multiple saved versions. Comparing version 3 to version 5 shows exactly what changed without reading both from beginning to end. Regulatory and compliance…
PDFWix's compare PDF tool identifies four types of differences between two documents. Text additions — words, sentences, or paragraphs present in the new version but not the original are highlighted in green. Easy to spot at a glance. Text deletions — content removed from the original that does not appear in the new version is highlighted in red. No deleted text goes unnoticed. Text modifications — content that exists in both versions but with different wording, numbers, or punctuation is flagged as a change. Useful for catching altered figures, dates, or names in contracts and reports. Layout and formatting differences — significant structural changes such as added or removed pages, reordered sections, or changed page numbering are surfaced in the comparison view. Note: scanned PDF…
**Legal teams:** Comparing contract redlines between drafts. When a counterparty returns a marked-up contract, PDF comparison identifies every change made — including subtle word substitutions that are easy to miss manually. **Compliance and audit teams:** Comparing policy documents, regulatory filings, or procedure manuals between versions to verify what changed and when. **Publishers and editors:** Proofreading galley proofs against the final typeset version — catching last-minute changes introduced during layout. **Software teams:** Comparing exported documentation PDFs between releases to verify change logs are complete. **Academic researchers:** Comparing pre-print and published versions of papers to identify changes made during peer review.
Yes. PDFWix's compare PDF tool is completely free with no daily task limits and no watermarks on output. No account or signup required.
Yes. The tool handles multi-page documents. Navigate through differences page by page using the comparison view.
PDF comparison works on text-based PDFs where the text is machine-readable. Scanned PDFs contain image data rather than text — run them through OCR PDF first to make the text selectable, then compare.
Yes. PDFWix's compare tool runs entirely in your browser — neither PDF file leaves your device. No upload to any server. Safe for confidential contracts, legal documents, and sensitive business files.
Yes. Download a redlined PDF showing all changes marked up, or export a summary of differences for sharing with colleagues or clients.
A text diff compares raw text strings. A PDF comparison tool understands document structure — it compares pages, paragraphs, and layout as a reader would, not just raw character strings. PDFWix shows differences in context so you can understand exactly what changed and where.
Yes. PDFWix Compare PDF handles documents with different page counts — for example, comparing a 10-page original with a 12-page revised version where two pages were inserted. The comparison engine aligns pages by content similarity, not by page number, so inserted or deleted pages are correctly identified rather than being flagged as a total mismatch.
Text file diffing (as used in Git or command line tools) compares plain text line by line. PDF comparison must first extract the text layer from both documents — which involves handling fonts, encoding, and layout — then compare the extracted text while also accounting for image differences and layout changes. PDFs also contain formatting, embedded images, and metadata that plain text tools cannot compare. PDFWix handles the full PDF structure, not just the text layer.
Open PDFWix Compare PDF, upload your original as File 1 and the revised version as File 2, and click Compare. PDFWix displays both documents side by side with every difference colour-coded — additions in green, deletions in red, changed text in amber. You can scroll through both documents simultaneously and download the marked-up comparison as a PDF. Free, no signup, runs in your browser.
PDFWix Compare PDF analyses the text content of both PDFs and identifies every added, deleted, or changed word or paragraph. Upload both files, click Compare, and the differences are highlighted in a side-by-side view. For scanned PDFs (images without a text layer), PDFWix uses OCR to extract text before comparing — this may take a few extra seconds for large scanned documents.
Yes. PDFWix Compare PDF produces a redline-style comparison — additions shown in green, deletions struck through in red, changes highlighted in amber. This is the standard format for contract and document review. Upload the original and the marked-up version, and PDFWix generates the redline view automatically. Download the comparison as a PDF to share with reviewers.
For scanned PDFs without selectable text, run OCR PDF first, then compare. To protect a document before sharing it for review, use protect PDF. To redact sensitive content from either version before comparing, use redact PDF.