Highlight PDF
Highlight, underline,
and annotate PDFs
Draw a highlight over any text to mark it up. Switch to underline or strikethrough in one click. Choose any colour and opacity level.
File never leaves your device
Four annotation types
Highlight
Fill behind text with a semi-transparent colour. Adjust opacity from 10% to 100%.
Underline
Draw a line under text — ideal for marking important passages without covering them.
Strikethrough
Cross out text to mark it as deleted or superseded. Common in edits and legal documents.
Freehand
Draw freely over the page — circle items, add arrows, or mark anything that doesn't fit a rectangle.
Frequently asked questions
Does highlighting change the original PDF text?
No. Highlights, underlines, and strikethroughs are overlaid on the page as annotations. The original text content of the PDF is not modified.
Can I choose the highlight colour?
Yes — you can pick any colour using the colour picker in the Properties panel, and adjust the opacity from fully transparent to fully opaque.
Will the highlights appear in Adobe Reader?
Yes. Annotations are embedded in the downloaded PDF as standard annotation objects, which are fully visible in Adobe Reader, Chrome, and any major PDF viewer.
Can I remove a highlight after placing it?
Yes. Select the highlight with the Select tool and press Delete, or use Cmd+Z to undo immediately after placing it.
Can I highlight scanned PDFs?
Yes — you can draw highlights over any PDF page regardless of whether it contains selectable text or is a scanned image.