Annotate a PDF

Annotate PDF Files Directly in Your Browser, Free, Private, Instant

iSharePDF's annotation tool lets you highlight text, add comments, draw shapes, and insert sticky notes on any PDF document. No software to install, no account to create, just open your file and start marking it up in seconds.

Your files never leave your device. All processing happens locally in your browser using client-side JavaScript. Nothing is uploaded to any server, which means your documents stay private whether they contain confidential contracts, medical records, or internal reports.

How to Annotate a PDF

1. Open your PDF. Click "Select file" or drag and drop your PDF onto the tool. The file loads instantly in your browser, no upload, no waiting.
2. Choose an annotation type. Pick from highlights, underlines, strikethroughs, freehand drawing, text boxes, or sticky note comments using the toolbar at the top.
3. Mark up your document. Click and drag to highlight passages, click to place a comment, or draw freely on any page. Annotations are editable and deletable at any time.
4. Save your annotated PDF. Click "Download" to export the finished file with all annotations embedded. The result opens in any standard PDF reader.

Why Use iSharePDF to Annotate PDFs

• Completely free. No subscription, no trial period, no hidden fees. The full annotation toolkit is available to everyone at no cost.
• 100% local, your browser does the work. The PDF is processed entirely on your machine. Closing the tab is enough to ensure nothing persists anywhere.
• Zero privacy risk. No server ever receives your file. Sensitive documents, NDAs, medical files, legal contracts, can be annotated without exposure.
• No watermarks added. Your exported PDF contains only the annotations you placed, nothing else. No branding, no stamps, no surprises.
• Unlimited use, any device. Annotate as many PDFs as you need, as often as you need, from any desktop or laptop browser without creating an account.

Common Use Cases

Researchers highlight key passages and add margin notes before citing sources. Students mark up lecture slides and textbook chapters for revision. Professionals reviewing contracts underline clauses, strike out outdated terms, and leave timestamped comments for colleagues, all without routing the document through a third-party cloud service.

Frequently Asked Questions

Is it safe to annotate a confidential PDF online?

Yes, because nothing actually goes "online" with iSharePDF. The file is loaded and processed entirely within your browser tab using JavaScript. No data is transmitted to external servers at any point, so there is no network exposure. You can verify this yourself by opening your browser's network inspector while using the tool, you will see no outbound file transfer.

Can I annotate a PDF without Adobe Acrobat?

Absolutely. Adobe Acrobat is not required. iSharePDF runs in any modern browser (Chrome, Firefox, Edge, Safari) and supports the standard annotation types most people need: highlights, underlines, text comments, freehand drawing, and sticky notes. The exported file is fully compatible with Acrobat and other PDF readers.

Will my annotations be visible to others when I share the PDF?

Yes. When you download the annotated PDF, all annotations are embedded directly into the file as standard PDF annotation objects. Anyone opening the file in a PDF reader, Acrobat, Preview, Foxit, or a browser, will see the highlights and comments exactly as you placed them.

Can I annotate a scanned PDF or image-based PDF?

You can place freehand drawings, shapes, and text boxes on any PDF page, including scanned documents. Text-based highlighting requires selectable text, so it works on native PDFs but not on flat image scans. If your scanned PDF has been processed with OCR beforehand, text selection will work normally.

Is there a file size limit for PDF annotation?

There is no hard server-side limit because no file ever reaches a server. The practical limit depends on your device's available RAM and browser capabilities. Most PDFs up to several hundred megabytes load without issues on a standard laptop. Very large files with hundreds of high-resolution pages may load more slowly on older hardware.