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🔒 100% Browser-Based • Private & Instant

Highlight Key Sections on PDF Pages

Place translucent neon highlight bars over key clauses or paragraphs on any PDF page.

📄

or drag and drop your file here

✅ Task Complete!

Continue Your Workflow (Next Recommended Steps):

Next: Add Comments to PDF → Next: Flatten PDF →

How to Use Highlight PDF 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 Highlight PDF Now to download your output immediately, or continue to related tools like Annotate PDF, Add Comments to PDF, Add Text to PDF.

Technical Specifications & Privacy Guarantee

Tool NameHighlight PDF (SYCAGO PDF Suite)
Accepted Input Formats.pdf (Single file)
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 Highlight PDF

Is the SYCAGO Highlight PDF tool completely free?

Yes. Highlight PDF 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 Highlight PDF?

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.

Related PDF Tools

Annotate PDF

Apply visual review banners, bordered callout boxes, and status stamps directly onto selected PDF pages.

100% Browser-Based Use Tool →

Add Comments to PDF

Stamp a formatted reviewer note card (with Reviewer Name, Date, and Comment text) onto the margin of any PDF page.

100% Browser-Based Use Tool →

Add Text to PDF

Type text directly onto any PDF page with customizable position, font size, and color.

100% Browser-Based Use Tool →

Extract Text from PDF

Read the native text layer of your PDF, preview it live on screen with word/character counts, and download as `.txt`.

100% Browser-Based Use Tool →

Compare PDF (Visual Diff)

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

100% Browser-Based Use Tool →
' + 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; } }); });