Liberook VS Diffee

Liberook's answer

• HTML, CSS, and vanilla JavaScript (single-file, no build step)
• PDF.js for parsing PDF files client-side
• JSZip for parsing EPUB files client-side
• Service Worker API for offline support and app shell caching
• Web App Manifest for PWA installability on iOS, Android, and desktop
• Cloudflare Workers for static hosting and edge delivery
• Cloudflare Web Analytics for privacy-respecting visitor analytics

Liberook's answer

The story is less technical than it looks. Young people around me are reading less and less — phones, short-form video, and endless scrolling have crowded out the patience a book requires. I wanted to meet them halfway: a reading format closer to the rhythms they already enjoy — fast, focused, a little like a game. Liberook flashes text one word at a time, includes a challenge mode that auto-accelerates as you go, and runs in any browser with no signup. The goal isn't to replace deep reading. It's to bring younger readers back to words — one word at a time.

Liberook's answer

Liberook is the only speed reader that's fully free, requires no account, runs entirely in the browser, and natively supports PDFs and EPUBs without conversion. It uses the Spritz-style RSVP technique with a highlighted focal letter, and adds a unique "challenge mode" — a guided training exercise that automatically accelerates you from 300 to 900 words per minute as cue phrases appear in the text. Installable as a Progressive Web App, works offline, no ads, no tracking.

Liberook's answer

Most speed reading apps push users toward subscriptions, paywalls, or ad-supported reading. Liberook takes the opposite approach: one clean interface, no signup, no email capture, no premium tier. You open the site, paste or upload your text, and start reading. It handles PDFs and EPUBs directly in the browser rather than forcing exports. It works offline once installed. And unlike most apps in the category, Liberook is transparent about what RSVP actually does — the site includes an article on what peer-reviewed research says about speed reading, so users know exactly what to expect.

Liberook's answer

Curious readers, students, knowledge workers, and productivity enthusiasts who want to get through more text in less time — articles, emails, newsletters, non-fiction books. Also people with large reading backlogs who need a fast way to triage what's worth reading deeply. Secondary audiences include language learners using RSVP to train reading fluency, and some dyslexic readers who find the single-word display easier to process than flowing text.