SUFX: Learn English by Reading

gavrichenko

In-app purchases

About this app

SUFX is a deep, AI-powered way to learn English — not just translate words, but understand and remember them.

Most learners look a word up and forget it a week later. SUFX turns every word you meet into lasting vocabulary: search it, see it in real context, save it, and practice until it sticks.

For example, SUFX can tell the difference between fine in "a fine day," "a fine distinction," and "pay a fine" from the sentence context.

WHAT YOU GET

• Ultra-detailed dictionary — meanings in context, IPA pronunciation (US & UK), CEFR level, frequency, word forms, collocations, synonym nuances, phrasal verbs, register, etymology, and learning tips.
• Smart context search — understand what a word really means in the sentence where you found it.
• Read in the original — public-domain English books, plus your own EPUB, FB2, and TXT files. Use a modern reader with themes, fonts, text size, and layout settings. Tap any word to translate it in context, ask the AI tutor, or save it.
• Build lasting vocabulary — save the words you meet and review them at the right time with flashcards and fill-the-gap exercises. Track progress, streaks, and mastery over time.
• AI tutor (Ask AI) — ask about any word or sentence: grammar, nuance, register, or how to use it.
• AI writing practice — write short essays and get clear, exam-style feedback: band scores, marked mistakes with explanations, and words to learn next.
• Your learning toolkit — curated word collections, custom lists, saved notes, pronunciation audio, instant translation, progress statistics, and daily streaks.

BUILT FOR SERIOUS LEARNERS
SUFX is for B1–C2 learners who want depth, context, and steady progress.

SUFX is free to download. A subscription unlocks higher daily limits, advanced review modes, and custom reading themes. Subscriptions renew automatically and can be managed or cancelled in your account settings. Terms of Use and Privacy Policy are available in the app.

Questions? Visit https://sufx.app/support or email [e-mail].

What’s new

• New: Tap a word while reading — it opens in a card over the page, so you stay in the book
• New: Contents — open any chapter and return to where you were
• Improved: The recap after reading shows your daily goal and saves every word you looked up at once
• Improved: A review session no longer loses your answers when the connection drops
• Fixed: Books that would not open, strange symbols in book text, and a streak that reset itself
Questions or ideas? Help & feedback in the app