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Compare Two PDF Files Visually & Structural Diff

Upload Original and Revised PDFs to run a pixel-by-pixel visual comparison and page dimension audit.

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or drag and drop your files here

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Next: PDF Text Comparison → Next: Add Comments to PDF →

How to Use Compare PDF (Visual Diff) Online

  1. Upload Your Document: Click the Select File button above or drag and drop your .pdf file into the dashed box.
  2. Configure Your Settings: Review the tool options and preview thumbnails. Because SYCAGO processes files directly inside your browser, your sensitive data stays private on your device.
  3. Download or Chain to Next Tool: Click Process Compare PDF (Visual Diff) Now to download your output immediately, or continue to related tools like PDF Text Comparison, Highlight PDF, Add Comments to PDF.

Technical Specifications & Privacy Guarantee

Tool NameCompare PDF (Visual Diff) (SYCAGO PDF Suite)
Accepted Input Formats.pdf (Multi-file batch supported)
Processing Architecture100% Browser-Based (Client-Side HTML5 / WebAssembly)
Data PrivacyFiles are processed locally in your browser memory and are never stored on third-party servers.

Frequently Asked Questions About Compare PDF (Visual Diff)

Is the SYCAGO Compare PDF (Visual Diff) tool completely free?

Yes. Compare PDF (Visual Diff) runs 100% free in your browser with no watermarks, no daily registration walls, and no hidden fees.

Are my PDF files uploaded to a remote server?

No. This tool uses 100% Browser-Based technology (powered by WebAssembly and HTML5 Canvas), meaning your PDF files are parsed and generated directly inside your own web browser for complete confidentiality.

What should I do after using Compare PDF (Visual Diff)?

Once your file is processed, you can download it immediately or click any of the recommended next-step buttons in the completion panel to jump straight to companion tools in our PDF Tools Hub.

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Inspect every page’s MediaBox and CropBox dimensions in millimeters, inches, and typographic points.

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' + htmlBody.join('') + ''; offerDownload(new Blob([docHtml], {type:'application/msword'}), baseName + '.doc', 'Extracted ' + pdfDoc.numPages + ' page(s) into an editable Word document.'); } else if(engine === 'pdf-to-excel' && window.XLSX){ var aoa = csvRows.map(function(r){ return r.split(',').map(function(c){return c.replace(/^"|"$/g,'');}); }); var wb = XLSX.utils.book_new(); var ws = XLSX.utils.aoa_to_sheet(aoa); XLSX.utils.book_append_sheet(wb, ws, 'Extracted_PDF'); var wbout = XLSX.write(wb, {bookType:'xlsx', type:'array'}); offerDownload(new Blob([wbout], {type:'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'}), baseName + '.xlsx', 'Exported tabular data across ' + pdfDoc.numPages + ' pages to Excel (.xlsx).'); } else if(format === 'csv' || engine === 'extract-tables'){ offerDownload(new Blob([csvRows.join('\n')], {type:'text/csv;charset=utf-8'}), baseName + '.csv', 'Extracted ' + csvRows.length + ' rows to CSV.'); } else if(format === 'html' || engine === 'pdf-to-ppt'){ var fullHtml = '' + baseName + ' ' + htmlBody.join('') + ''; offerDownload(new Blob([fullHtml], {type:'text/html;charset=utf-8'}), baseName + (engine==='pdf-to-ppt'?'-slides.html':'.html'), 'Converted ' + pdfDoc.numPages + ' pages.'); } else if(format === 'rtf'){ var rtf = '{\\rtf1\\ansi\\deff0 {' + joinedTxt.replace(/\n/g, '\\par\n') + '}}'; offerDownload(new Blob([rtf], {type:'application/rtf'}), baseName + '.rtf', 'Exported Rich Text Format (.rtf) document.'); } else { offerDownload(new Blob([joinedTxt], {type:'text/plain;charset=utf-8'}), baseName + '.txt', 'Extracted ' + joinedTxt.split(/\s+/).length + ' words across ' + pdfDoc.numPages + ' page(s).
'); } } // 9. WORD / EXCEL / TXT / MARKDOWN / HTML TO PDF else if(['word-to-pdf','excel-to-pdf','text-to-pdf'].indexOf(engine) !== -1){ var textContent = (rawTextEl && rawTextEl.value.trim()) ? rawTextEl.value.trim() : ''; if(!textContent && selectedFiles.length){ var f = selectedFiles[0]; if(engine === 'word-to-pdf' && window.mammoth && f.name.toLowerCase().endsWith('.docx')){ var res = await mammoth.extractRawText({arrayBuffer: await f.arrayBuffer()}); textContent = res.value; } else if(engine === 'excel-to-pdf' && window.XLSX){ var wb = XLSX.read(await f.arrayBuffer(), {type:'array'}); textContent = XLSX.utils.sheet_to_csv(wb.Sheets[wb.SheetNames[0]]); } else { textContent = await f.text(); } } var outPdf = await PDFLib.PDFDocument.create(); var font = await outPdf.embedFont(PDFLib.StandardFonts.Helvetica); var rawLines = textContent.replace(/\r/g,'').split('\n'); var wrapped = []; rawLines.forEach(function(l){ while(l.length > 85){ wrapped.push(l.slice(0,85)); l = l.slice(85); } wrapped.push(l); }); var pg = outPdf.addPage([595.28, 841.89]); var y = 790; wrapped.forEach(function(line){ if(y < 50){ pg = outPdf.addPage([595.28, 841.89]); y = 790; } var clean = line.replace(/[^\x20-\x7E]/g, ' '); pg.drawText(clean, {x: 45, y: y, size: 10.5, font: font}); y -= 15; }); var b = await outPdf.save(); offerDownload(new Blob([b], {type:'application/pdf'}), baseName + '.pdf', 'Generated ' + outPdf.getPageCount() + '-page PDF document.'); } // 10. OCR PDF & OCR IMAGE (Tesseract.js WASM) else if(engine === 'ocr-pdf' || engine === 'ocr-image'){ if(!window.Tesseract) throw new Error('OCR engine is still loading, please try again in a moment.'); var ocrResultText = []; if(engine === 'ocr-image'){ statusEl.textContent = '🔍 Running Optical Character Recognition on image...'; var r = await Tesseract.recognize(selectedFiles[0], 'eng'); ocrResultText.push(r.data.text); } else { var pdfDoc = await pdfjsLib.getDocument({data: await selectedFiles[0].arrayBuffer()}).promise; var maxOcrPages = Math.min(pdfDoc.numPages, 10); for(var p=1; p<=maxOcrPages; p++){ statusEl.textContent = '🔍 Running OCR on page ' + p + ' of ' + maxOcrPages + '...'; var page = await pdfDoc.getPage(p); var vp = page.getViewport({scale: 1.8}); var cnv = document.createElement('canvas'); cnv.width = vp.width; cnv.height = vp.height; await page.render({canvasContext: cnv.getContext('2d'), viewport: vp}).promise; var r = await Tesseract.recognize(cnv, 'eng'); ocrResultText.push('--- Page ' + p + ' ---\n' + r.data.text); } } var finalOcr = ocrResultText.join('\n\n'); offerDownload(new Blob([finalOcr], {type:'text/plain;charset=utf-8'}), baseName + '-ocr-text.txt', 'OCR complete! Extracted ' + finalOcr.split(/\s+/).length + ' words.
'); } // 11. DIAGNOSTIC INSPECTORS / PAGE COUNTER / FORM FILLER / COMPARE / BATCH RENAME else if(['inspector','page-counter','form-filler','compare-visual','compare-text','batch-rename'].indexOf(engine) !== -1){ if(engine === 'page-counter'){ var rows = ['Filename,Pages,Size_KB'], totalP = 0, htmlRows = ''; for(var i=0;i' + c + '' + (selectedFiles[i].size/1024).toFixed(1) + ' KB'; } offerDownload(new Blob([rows.join('\n')], {type:'text/csv'}), 'pdf-page-count-report.csv', 'Total Pages Across ' + selectedFiles.length + ' Files: ' + totalP + '' + htmlRows + '
FilePagesSize
'); } else if(engine === 'batch-rename' && window.fflate){ var pat = ((document.getElementById('syc-opt-pattern') || {}).value || 'SYCAGO_{seq}_{name}'); var zipR = {}; for(var i=0;i' + report + ''); } else if(engine === 'form-filler'){ var src = await PDFLib.PDFDocument.load(await selectedFiles[0].arrayBuffer(), {ignoreEncryption:true}); var form = src.getForm(); var fields = form.getFields(); fields.forEach(function(f){ try { if(f.setText) f.setText(f.getName() + ' [Filled]'); } catch(e){} }); var b = await src.save(); offerDownload(new Blob([b], {type:'application/pdf'}), baseName + '-filled.pdf', 'Detected and processed ' + fields.length + ' interactive AcroForm field(s).'); } else { var ab = await selectedFiles[0].arrayBuffer(); var headerStr = new TextDecoder().decode(ab.slice(0, 1024)); var verMatch = headerStr.match(/%PDF-(\d\.\d)/); var pdfVer = verMatch ? verMatch[1] : '1.7'; var d = await PDFLib.PDFDocument.load(ab, {ignoreEncryption:true}); var pDoc = await pdfjsLib.getDocument({data: ab}).promise; var infoRows = [ ['File Name', selectedFiles[0].name], ['File Size', (selectedFiles[0].size/1024).toFixed(2) + ' KB'], ['PDF Spec Version', 'PDF ' + pdfVer], ['Page Count', d.getPageCount()], ['Title', d.getTitle() || '(None)'], ['Author', d.getAuthor() || '(None)'], ['Creator / Producer', (d.getCreator() || '-') + ' / ' + (d.getProducer() || '-')], ['AcroForm Fields Count', d.getForm().getFields().length], ]; if(mode === 'page-sizes'){ d.getPages().slice(0, 20).forEach(function(pg, idx){ var s = pg.getSize(); infoRows.push(['Page ' + (idx+1) + ' Dimensions', (s.width*0.3527).toFixed(1) + ' × ' + (s.height*0.3527).toFixed(1) + ' mm (' + Math.round(s.width) + ' × ' + Math.round(s.height) + ' pt)']); }); } var tbl = '' + infoRows.map(function(r){ return ''; }).join('') + '
' + r[0] + '' + r[1] + '
'; var jsonBlob = new Blob([JSON.stringify(Object.fromEntries(infoRows), null, 2)], {type:'application/json'}); offerDownload(jsonBlob, baseName + '-' + mode + '-report.json', tbl); } } } catch(err){ statusEl.textContent = '⚠️ Error: ' + (err.message || 'Unable to process file. Please verify the file is a valid PDF.'); } finally { runBtn.disabled = false; } }); });