FocusRuler

A precision reading ruler for papers and PDFs. Inspired by the optical slit — isolate one line, silence the rest.

FocusRuler is a reading ruler for Chrome, designed for anyone who reads long-form documents seriously — research papers, technical documentation, PDFs, and web articles. ── HOW IT WORKS ── A frosted-glass slit overlays the page, highlighting the line you're reading while the surrounding content fades into a blurred, darkened overlay. Visual noise disappears. Your focus narrows. You read faster and retain more. ── TEXT ECHO ── Copy any term or definition while reading (Cmd+C / Ctrl+C). FocusRuler saves it and watches for the same word as you scroll. When it reappears, a panel instantly surfaces the original sentence where you first encountered it — no more flipping back to page 2 to recall a definition introduced there. ── KEYBOARD FIRST ── • Alt+R — Toggle ruler on / off • Alt+↑ / Alt+↓ — Move ruler up or down (works inside Chrome's PDF viewer) • Alt+Scroll — Resize ruler height • Cmd+C / Ctrl+C — Save term to Text Echo ── FULLY CUSTOMISABLE ── Adjust ruler height, blur intensity, overlay darkness, and accent colour from the popup. Settings sync automatically across Chrome profiles. ── PRIVACY ── FocusRuler runs entirely on your device. No data is collected, transmitted, or stored on any server. Clipboard access is used only for the Text Echo feature and stays in memory for the duration of your session. ── PDF SUPPORT ── Works on local PDF files too. Enable "Allow access to file URLs" in the extension settings to use FocusRuler on PDFs opened directly in Chrome.