How to highlight and annotate a PDF for free

1 min read·25 July 2026

Highlighting text, underlining, or adding notes to a PDF can be done with PDFrust directly in your browser. Perfect for students, researchers, and anyone who wants to comment on documents without expensive software.

Highlight text in a PDF

The highlight tool in PDFrust lets you apply coloured highlights over text sections in your PDF. Choose the colour, select the text area, and download the PDF with the highlight. The original text is fully preserved.

Stamps and icons as annotations

Beyond highlighting you can also add stamps: "Approved", "Draft", "Confidential". PDFrust provides standard stamps plus the ability to use your own images as stamps.

Add watermark

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Add text as a comment

The text overlay tool lets you place text blocks on top of the PDF page. This lets you add remarks, corrections, or explanations to a document without changing the original text.

Great for collaboration documents

Annotate a draft quote before emailing it back. Highlight the points that still need discussion. Download the annotated version and send it to your colleagues — no app needed.