Highlight Text in PDF Online
Highlight, underline and strike through — free
To highlight a PDF, open it above — a yellow highlighter is placed on the first page. Drag and stretch it over the text you want to mark, add more with the Highlight tool, and use Underline or Strike for other marks. Click Save PDF to download your marked-up copy. Nothing is uploaded.
Open a PDF to start editing
Your files never leave your device
How to make a highlight pdf
Open the PDF
Choose the document to mark up.
Highlight
Add highlights, underlines or strikethroughs and stretch them over the text. Add notes with Text and arrows.
Save PDF
Download the annotated PDF.
Marking up documents
Highlights draw attention to key sentences in contracts, study material and reports; underlines emphasise; strikethrough shows deletions in a review. Pair them with text notes and arrows to explain changes — useful when sending feedback on a draft or preparing study notes.
How highlights are saved
Fylo saves highlights as semi-transparent shapes on the page, so they look identical in every PDF reader — including browsers, phones and printers that ignore annotation layers. The text underneath stays selectable.
Study and review workflows
Students can use yellow for key definitions, green for examples and pink for things to revisit, then save a marked-up copy alongside the clean original. Reviewers can strike through text to be removed, underline what needs checking and add short text notes in the margin with an arrow pointing to the passage. Everything is saved into a single PDF that anyone can open, without needing special annotation support.
Highlights are semi-transparent, so overlapping marks deepen in colour — avoid stacking them on the same line.
Frequently asked questions
Can I change the highlight colour?
Yes — select the highlight and pick a colour in the Selected panel.
Can highlights be removed later?
They're part of the saved page. Keep your original PDF if you may need an unmarked copy.
Is the text still searchable?
Yes, highlighting doesn't affect the original text.
Can I highlight scanned PDFs?
Yes, highlights can be placed on any page.
Can I add comments next to highlights?
Yes. Use the Text tool to type a note in the margin and an arrow from Shapes to point at the passage.
Can I make highlights thinner for single lines?
Yes, drag the top or bottom handle to fit one line of text.
Can I make highlights thinner for single lines?
Yes, drag the top or bottom handle to fit one line of text.
Are my files uploaded to a server?
No. Highlight PDF runs entirely in your browser — your files are processed on your own device and never sent anywhere. Once the page has loaded, it even keeps working if your connection drops.
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