Mark up PDF

Highlight, underline or strike out text, draw shapes and pin notes — saved as real PDF annotations, all on your device.

About this tool

Annotate PDF — Highlight, Underline, Draw and Add Notes

Highlight, underline or strike out text, draw shapes and pin notes, then download the marked-up file. Everything runs locally in your browser — no upload, no sign-up, no watermark and no file size limit.

Highlight the Words Themselves

Drag across a line and the highlight snaps to the text, so it covers exactly the words you picked at any zoom.

Real PDF Annotations

Markup is saved as standard PDF annotations, so Acrobat, Preview and browser viewers show it and can still edit or remove it.

Shapes, Arrows and Notes

Box or circle a figure, draw a line or arrow, or pin a note with your comment, in the colour and stroke width you choose.

How to use it

  1. Drop the PDF you want to review. Pages open in the editor with the markup toolbar above them.
  2. Pick Highlight, Underline or Strikethrough and drag across the words you mean; the mark snaps to the text.
  3. For figures and layout comments, choose Rectangle, Ellipse, Line or Arrow and drag on the page. Note pins a comment you can type into.
  4. Tap any mark to change its colour or line width, move it or delete it. Every mark is also listed with its page number, so you can jump back to it.
  5. Download the annotated PDF and send it on. Your reviewer can open the marks in any PDF viewer.

Frequently asked questions

Are my PDFs uploaded to a server?

No. Toolula processes the document inside your browser tab with pdf-lib and WebAssembly, so the file never leaves your device.

Can others remove my highlights?

Yes, annotations stay editable in PDF viewers. To make them permanent, run the file through Flatten PDF afterwards.

Can I highlight a scanned PDF?

Text marks need real text, which a scan does not have. Draw a rectangle or an ellipse around the passage instead, or pin a note next to it.

Is it really free?

Yes. You can use every Toolula PDF tool for free, without an account. The free plan has fair-use limits; Toolula Pro, an optional plan, raises them and adds advanced features.