Highlight, underline, strike through
Mark up text exactly like you would with a pen, in five highlighter colors.
The margins your PDFs never had.
Highlight, underline, sketch, and leave notes on any PDF — right inside Chrome. Everything you mark is saved as a real PDF annotation, so it's still there in Acrobat, Preview, or anywhere else you open the file.
No account. No server. Your PDFs and notes never leave your browser.
What you can do with it
Draw freehand
Circle a paragraph, sketch a diagram, underline something a highlight can't quite catch.
Notes in the margin
Pin a note next to any passage, exactly where it belongs — not in a separate app.
Real annotations, not just pixels
What you mark is saved as a standard PDF annotation — open the file in Acrobat, Preview, or anywhere else, and it's still there.
Opens every PDF automatically
Click a PDF link anywhere on the web and Marginalia is already open, tools ready.
Stays on your machine
No account, no server, no upload. Your documents and notes never leave your browser.
See it in action
A few screens from the extension. Click any of them for a closer look.
Marginalia is free. It always will be for personal use.
There's no premium tier, no paywall, no account wall. If it saves you time and you'd like to help keep it maintained, a small one-time or monthly gift genuinely helps — but it's never required.
A few questions
- Does Marginalia cost anything?
- No. It's free to install and use, with no limits and no account required.
- Where are my highlights and notes stored?
- Locally, in your browser. Marginalia doesn't have a server, so nothing about your documents or notes is ever sent anywhere.
- Will my annotations show up if I open the PDF somewhere else?
- Yes. Once you save or export, your marks are written as standard PDF annotations, so they'll show up in Acrobat, Preview, or any PDF reader that supports annotations.
- Which PDFs does it work with?
- Any PDF you can open in Chrome — from a link, a download, or a file already on your computer.