Slate Focus – Reading Ruler & Focus Mode

About

Slate Focus adds a reading ruler and focus mode to any web page. Click the toolbar icon (or set your own keyboard shortcut) and everything on the page dims except a soft band that follows your mouse — so your eyes stay locked on what you're reading instead of drifting across a wall of text.
Toggling Focus Mode is always free. Slate Focus Premium ($5, one-time — no subscription) unlocks full customisation:

Spotlight height and dim strength
Overlay color
Font size and paragraph width
Edge softness (hard-edged or soft-faded band)

Built for privacy from the ground up: no account, no sign-in, no tracking, no analytics. Your settings never leave your device, and Slate Focus only ever touches the tab you're actively using — it can't read your other tabs or your browsing history.
Great for long articles, dense documentation, or just reading comfortably after a long day of screens.