Highlight PDF
Highlighting a PDF means marking a stretch of text with a coloured overlay so you can find it again later. PDF Annotator works as a PDF online highlighter right in your browser — no upload, no signup.
Highlight text right on the page
Highlighting is three quick moves:
- Drop a PDF into the app.
- Pick up the highlighter.
- Drag across the text you want to mark.
The colour lands on the exact character run, not a rectangle on top — so the text underneath stays readable. It's the same feel as a paper marker, except the file stays on your device the whole time. Close the tab, come back, and your highlights are still there.
Colours and marker styles
Yellow is the default because that's how print-friendly PDFs open in most readers. Switch colours when you're marking different themes side by side:
- Yellow — default; matches most PDF readers.
- Green — quotes and evidence.
- Pink — questions or things to come back to.
- Blue — references and links.
Every colour keeps the same low opacity so the text underneath stays legible.
Scanned PDFs — the honest limit
A scanned PDF is really an image inside a PDF wrapper. If your document has no selectable text, the highlighter can't find any characters to mark. You'll need OCR first (Adobe Acrobat has one, or a stand-alone OCR pass) — after that, come back and highlight in your browser.
Related tools
Need to type on the page instead? Write on PDF. To sign, fill forms, or draw shapes, go back to the main annotator.