How to Annotate a PDF Online: Highlight, Draw and Add Notes

PDFly guide · Updated October 2026

Reading a PDF is rarely the end of the job. You want to highlight a sentence, circle a figure, write "check this" next to a clause and send the marked-up copy to someone. PDFly's Annotate PDF tool does that in your browser, and the file never leaves your device.

Step by step

1. Open the PDF. Drop it on the Annotate PDF page. Every page appears in a scrolling view you can zoom.
2. Pick a tool. Highlighter, pen, text, rectangle, ellipse, line or arrow. Each tool remembers its own colour, and you can choose from seven swatches or any custom colour.
3. Mark the page. Drag across a sentence to highlight it, circle a number with the ellipse, or click to type a note.
4. Fix mistakes. Undo and Redo work as you would expect. The Select tool moves or deletes an item, and the Eraser rubs items out. Double-click a text note to edit it.
5. Download. Press Download PDF and your markings are added on top of the original pages as a new file. The original is not changed.

The laser pointer

Press K to switch to the laser pointer. A red trail follows your mouse and fades after a second, which is useful when you share your screen and talk through a document. It is never saved into the file.

Keyboard shortcuts

V select, P pen, H highlighter, T text, R rectangle, O ellipse, A arrow, L line, E eraser, K laser. Ctrl+Z undoes and Ctrl+Shift+Z redoes. There is also a dark view and a full-screen mode for long reading sessions.

Good to know

• Annotations are a layer. They are drawn as pictures on top of the page, so the original text stays selectable but your notes are not searchable.
• Password-protected files must be unlocked first.
• Pages rotated inside the file are not supported yet.
• Need to sign instead? Use Sign PDF. Need to hide sensitive text? Use Redact PDF.