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    Find Text Differences Between Two PDF Versions

    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.

    Rated 4.6/5 by 122 users

    Updated July 2026 · Reviewed by the PDFWix Team

    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 is also called PDF diff, document redlining, change tracking, or version comparison — all refer to identifying what changed between two versions of the same document.

    To compare two PDF files online free: open PDFWix Compare PDF, upload your original PDF as File 1 and the revised version as File 2, and click Compare. PDFWix highlights additions in green, deletions in red, and changes in amber in a side-by-side view. Download the annotated comparison as a PDF. Free, no signup, runs in your browser.

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    Open Compare in PDF Studio — put two versions side by side and see every change highlighted.

    Compare your PDFs in PDF Studio

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    Open Compare in PDF Studio — put two versions side by side and see every change highlighted.
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    How to Check What Changed Between Two PDFs

    1. 1

      Upload your two PDF files

      Upload your two PDF files — the original version and the revised version. Drag both into the upload areas or click to select from your device.

    2. 2

      Review the comparison

      PDFWix analyses both documents and highlights every difference: added text, deleted text, and changed content. Results are displayed in a side-by-side view with changes colour-coded for quick scanning.

    3. 3

      Download the result

      Review each highlighted change. Navigate through differences page by page. Download a marked-up comparison report or the redlined PDF if needed.

    When Do You Need to Compare Two PDF Files?

    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 filings — amendments to policy documents, regulatory submissions, or compliance frameworks need to be reviewed precisely. A PDF diff shows every change with no ambiguity. Detecting unauthorised edits — a PDF sent to a client and returned for signature should be identical to the original. Running a comparison confirms the document has not been modified between sending and signing. Academic and research documents — comparing a submitted draft against a peer-reviewed final version, or checking a translated document against the source, reveals every change efficiently. To protect a document before sharing it for review, password protect PDF.

    What Does a PDF Comparison Tool Detect?

    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 documents contain image data rather than machine-readable text. PDF comparison works on text-based PDFs. For scanned documents, use OCR PDF first to make the text selectable before comparing.

    Who uses PDF comparison — and for what

    **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.

    Tips for comparing PDFs

    Same source matters

    Comparing a Word-exported PDF to a scanned PDF won't work cleanly — OCR introduces noise. Compare same-format files.

    Page-by-page sync

    If pages were inserted, the comparison may misalign. Organize PDF pages to sync structures first.

    Text-only mode for big files

    Visual diff is slow on 200+ page PDFs. Switch to text mode to highlight content changes only.

    OCR scans first

    If one version is a scan, run OCR PDF so text is comparable, not just pixels.

    Export the diff report

    Save the comparison as a third PDF — useful for circulating to stakeholders who weren't in the call.

    How PDFWix PDF comparison compares

    Feature PDFWix iLovePDF Adobe Acrobat Online Draftable
    Free, no daily limit ✓ Always ✗ 2 tasks/day ✗ Limited free ✗ Free trial
    No signup required ✓ Never ✗ Required ✗ Required ✗ Required
    Side-by-side view ✓ ✓ ✓ ✓
    Colour-coded changes ✓ ✓ ✓ ✓
    Works on scanned PDFs ✓ (OCR) ✓ ✓ ✓
    Download diff report ✓ ✓ ✓ ✓
    Files stay in browser ✓ WebAssembly ✗ Server ✗ Server ✗ Server

    Comparison based on publicly documented free tier limits as of June 2026.

    Why compare PDFs with PDFWix?

    • Text and visual diff in one pass. Text mode catches word-level changes; visual mode catches layout, image and formatting changes. Run both by default so a moved logo or restyled heading doesn't sneak past.
    • Side-by-side view. Original on the left, revised on the right, with synchronized scrolling. The classic redline workflow lawyers and editors already know.
    • Inline color-coded highlights. Additions in green, removals in red, visually changed regions boxed in yellow. The legend is consistent so review goes fast.
    • Exportable diff report. Save the comparison as a third PDF you can email to stakeholders. The report shows both versions plus the highlighted changes — perfect for sign-off circulation.
    • Browser-side. Compare confidential drafts (contracts, M&A docs, internal proposals) entirely on your device — neither file touches our server.
    • Free, no signup, no watermark. Compare as many drafts as you need without paying or registering. The exported diff report is clean of PDFWix branding.

    For scanned PDFs without selectable text, run OCR PDF first, then compare. To protect a document before sharing it for review, protect PDF. To redact sensitive content from either version before comparing, use redact PDF.

    Common uses for PDF comparison

    • Spotting redline edits between two contract drafts before signing
    • Verifying a final design spec matches the version the client approved
    • Checking that a revised research paper addresses every reviewer comment
    • Confirming a vendor's revised SOW matches what was agreed in the call
    • Comparing a published policy to its previous version for a change-log post
    • QAing a redacted PDF against the original to confirm only the right content was removed

    Frequently asked questions

    Is it free to compare PDF files online?

    Yes. PDFWix's compare PDF tool is completely free with no daily task limits and no watermarks on output. No account or signup required.

    Can I compare PDFs with many pages?

    Yes. The tool handles multi-page documents. Navigate through differences page by page using the comparison view.

    Does PDF comparison work on scanned PDFs?

    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.

    Are my documents private when comparing PDFs online?

    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.

    Can I download the comparison results?

    Yes. Download a redlined PDF showing all changes marked up, or export a summary of differences for sharing with colleagues or clients.

    What is the difference between comparing PDFs and diffing text files?

    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.

    Can PDFWix compare PDFs that have different page counts?

    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.

    How is comparing PDFs different from diffing text files?

    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.

    How do I compare two PDF files side by side for free?

    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.

    How do I find differences between two PDF documents?

    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.

    Can I compare a PDF redline for free?

    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.

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