Compare PDF Files Online

Compare two PDFs side by side, detect visual and text changes page by page, scan the complete documents, and download clear difference results.

PDF comparison workspace

Original PDF

Drop the earlier version here or browse your device.

Revised PDF

Drop the newer version here or browse your device.

Visual render quality

Difference sensitivity

Difference view

Preparing comparison0%

Current page of 1

Fit

Original PDFPDF A

This PDF does not contain the selected page.

Revised PDFPDF B

This PDF does not contain the selected page.

Detected differencesDiff

A difference view is unavailable for this page.

Original text with removalsPDF A

Revised text with additionsPDF B

Full-document scan results

Visual and text PDF comparison in one tool

Use visual comparison for layouts, images, stamps and scanned pages, or switch to text comparison for additions, removals and wording changes.

Visual pixel comparison

Detect moved elements, image swaps, stamps, signatures, formatting changes and page-size differences.

Word-by-word text diff

Mark removed words in the original and added words in the revised document without sending text to a server.

Whole-document scan

Process each corresponding page, identify changed or missing pages and jump directly to any result.

Different page counts

Pages present in only one PDF are clearly flagged rather than silently skipped.

Adjustable sensitivity

Reduce scanner noise or increase sensitivity for subtle color and antialiasing differences.

Downloadable results

Save a current-page PNG, a multi-page difference PDF, a TXT text diff or a structured JSON report.

How to compare two PDF files online

The workflow keeps both source documents visible and lets you inspect individual pages or scan the complete pair.

Add both PDFs

Select the original document as PDF A and the revised document as PDF B.

Choose a comparison mode

Use Visual for page appearance or Text for additions and removals in selectable text.

Review or scan

Navigate page by page, adjust sensitivity, or scan the entire document pair with progress and cancellation.

Save the result

Download a page-level PNG or TXT result, a complete difference PDF, or a JSON comparison report.

Where PDF comparison is useful

Document comparison helps confirm that revisions are intentional before a file is approved, signed, printed or distributed.

Contracts and agreements

Find revised clauses, figures, signatures, stamps, page insertions and formatting changes.

Reports and proposals

Compare draft and final versions of business reports, proposals and project documents.

Academic documents

Review thesis, assignment and research-paper revisions before submission.

Invoices and records

Verify corrected totals, dates, identifiers and line items in revised financial documents.

Privacy, accuracy and practical limits

Local browser processing

The PDFs, extracted text and comparison results are processed in your browser. CorrectionCopy does not receive the documents or their contents.

No Firebase counter, public rating database or document upload is used.
Analytics events contain only broad tool actions, never filenames, text or comparison results.
Reset and page exit release loaded PDF documents, workers and temporary resources.

What comparison can and cannot prove

A visual or text diff identifies detectable differences; it does not certify legal authenticity, authorship or cryptographic integrity.

Visual mode is strongest for scans, images, layout and formatting.
Text mode requires selectable text and is not OCR.
Large or image-heavy PDFs depend on available device memory and can take longer to scan.

Troubleshooting

Use these checks when a PDF does not load, a comparison looks noisy or a full scan cannot finish.

One of the PDF files does not open.

Confirm that the file is a genuine PDF. Password-protected, corrupted, partially downloaded or incorrectly renamed files must be unlocked, repaired or downloaded again.

The visual comparison marks many tiny differences.

Increase the sensitivity threshold or use Fast quality. Scanned pages, different PDF producers, font rasterization and antialiasing can create small pixel-level variations.

Text comparison shows little or no text.

The selected page may be a scan or image-only page without selectable text. Use Visual comparison, or apply OCR in a separate tool before comparing text.

The PDFs use different page sizes or orientations.

Visual comparison renders both pages at one shared scale and flags the unmatched area. Large size or orientation differences can therefore produce a high changed percentage.

A full-document scan is slow.

Visual scanning renders every page pair. Keep Balanced or Fast quality selected, close memory-heavy tabs and leave this page active. You can cancel without losing the loaded PDFs.

The browser runs out of memory.

Use a desktop browser, close other tabs and compare smaller document sections. The tool processes pages progressively but very large scans still depend on available device memory.

The difference download does not start.

Allow downloads for CorrectionCopy, verify available storage and retry. On mobile devices, check the browser download manager or Files app.

A content blocker prevents the PDF engine from loading.

The current stable PDF.js components load only after a PDF is selected. Allow the pinned dependency host for this page or retry without restrictive script blocking.

Compare PDF files FAQ

How do I compare two PDF files online for free?

Add the original and revised PDFs, choose Visual or Text comparison, review the current page or scan all pages, then download the difference result or report.

What is the difference between visual and text comparison?

Visual comparison detects pixel-level changes in text, images and layout. Text comparison extracts selectable text and marks removed and added tokens.

Can I compare scanned PDF documents?

Yes. Use Visual comparison for scanned pages. Text comparison does not perform OCR and therefore cannot read text that exists only inside an image.

Can I scan the complete PDF pair?

Yes. Scan all pages processes corresponding pages progressively, records unchanged, changed and missing pages, and provides jump buttons for review.

What happens when the PDFs have different page counts?

The comparison uses the longer document as the total. A page that exists in only one PDF is marked as missing from the other and treated as changed.

Can I reduce false differences from scans or font rendering?

Yes. Raise the Difference sensitivity value to ignore smaller color changes. Lower values detect subtler differences.

Can I download the comparison result?

Yes. Download the current visual page as PNG, the current text comparison as TXT, all visual difference pages as one PDF, or a structured JSON report.

Does the tool upload or store my PDFs?

No. PDF parsing, page rendering, text extraction and difference calculations occur in the browser.

Does a zero-difference result prove the PDFs are identical files?

No. The tool compares rendered page appearance or extracted text. Metadata, hidden objects, embedded files, signatures and internal PDF structure can differ without changing the selected comparison result.

Is there an artificial file-size or page-count limit?

No fixed lower limit is imposed by the interface. Practical capacity depends on browser support, document complexity, available memory and the selected render quality.