Annotate PDF

What does the Annotate PDF tool do?

The FreePDF Annotate tool opens your document in the browser editor with drawing, text and highlighting tools. Mark up pages with freehand strokes, notes and colour highlights — without printing anything.

Annotations are stored as an overlay in the editor and written into the PDF on export with pdf-lib. The original content stays intact underneath.

How to annotate

1. 1
   Open your PDF in the editor

   Drag and drop the document you want to mark up.

2. 2
   Pick an annotation tool

   Draw for freehand marks, Text for notes, Highlight for colour markers.

3. 3
   Annotate the pages

   Work through the document — thumbnails make it easy to jump between pages.

4. 4
   Download the annotated PDF

   Your annotations are written into the document in your browser on export.

What FreePDF Annotate PDF can do

• Freehand drawing and highlight colours
• Text notes anywhere on the page
• Per-page navigation with real thumbnails
• Works entirely in your browser

Privacy — your files stay on your device

Annotate PDF runs entirely inside your browser using the same open-source engine stack that powers all FreePDF tools. Your files are loaded into browser memory, processed on your CPU, and written back out as a direct download. Nothing is sent to any server — you can verify this in your browser devtools → Network tab. Close the tab and everything is cleared from memory.

Supported devices and browsers

Known limitations

FreePDF is honest about what it can and cannot do:

• Annotations are overlays — original content is not modified
• Freehand drawing export is rasterised
• Comment threads like desktop PDF apps are not supported