penciled

penciled is a free, open-source browser extension for highlighting text and adding notes on any webpage.

Select text, save a highlight, optionally add a note, and come back later — your marks stay on the page. No account. No cloud sync. Nothing leaves your browser.

Built on the open-source penciled library (CSS Custom Highlight API, no DOM wrapping), so highlights don’t break the page layout the way older “wrap the text in a span” tools often do.

Works on Chrome, Firefox, and Edge. MIT licensed.

Install: Chrome Web Store, Firefox Add-ons, or Microsoft Edge Add-ons. Library & docs: https://penciled.org