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Annotate PDF Online Free — PrivaTools

TL;DR: Upload a PDF and add highlights, sticky notes, text boxes, and shapes — download a copy with standard PDF annotations.

Annotate PDF online for free — add highlights, underlines, strikethrough, and sticky notes with customizable colors. Perfect for reviewing documents, studying, and collaborative feedback. No software needed.

Every PrivaTools tool — including Annotate PDF — is genuinely free with no premium tier, no per-day limit, and no watermark on the output. Files are deleted from the server within seconds of your download completing. Source code: github.com/taiyeba-dg/privatools.

How to Annotate PDF with PrivaTools

  1. Upload your PDF — Drop a PDF up to 500 MB.
  2. Add annotations — Use the toolbar to add highlights, underlines, strikethroughs, sticky notes, and text boxes. Each annotation has a position, page, content, and color.
  3. Save and download — Click Save. Annotations are added as standard PDF annotation objects — they appear in every PDF reader and can be edited later.

Frequently Asked Questions

Are annotations flattened?

By default no — they remain as editable annotations. If you want them permanently baked into the page, run the Flatten tool afterwards.

Can I attach sticky-note comments?

Yes. Add a note annotation with author + content; readers display it as an icon that opens a popup with the text on click.

Do annotations survive PDF/A conversion?

Some do (text, highlight, square) but interactive ones (file attachments, popup notes) get flattened or stripped depending on the PDF/A profile.

Last reviewed 2026-05-01 by the PrivaTools maintainers. Source code on (MIT-licensed, self-hostable).

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