AI-driven translation exercises, grammar correction, and pronunciation coaching - designed for real ESL learners worldwide.
Teaching English? Explore the teacher tools
Not just another flashcard app. Real grammar intelligence, real-time feedback.
1500 grammar rules are checked before any AI call. Hard rules always win - "a university" is always correct, no matter what the model thinks.
Visual progress rings transition from red to emerald as your score improves. See exactly where you stand on every exercise.
Hear the native-speaker version at 0.9× speed for clarity, then hear your own translation played back to spot flow issues.
GDPR, COPPA, POPIA, Egypt PDPL, LGPD - smart age gates and parental consent flows for every jurisdiction.
Tap any underlined error to see the exact grammar rule that applies. No vague feedback - specific, citable corrections.
Teachers can assign exercises, track class progress, and set daily challenges - built for real ESL classrooms.
Bring your teaching together with shared live lessons, ready-to-read articles and practical classroom ideas. Keep students practising in the Android app or their browser between lessons.
Teach together on the website
Create a session on the website and send its student link. Students log in or sign up free, then work through the same lesson on their own devices. Keep your video or audio call open alongside it.
Choose ready-made material from the Lesson Library or create your own exercises. Students can request a Library lesson for you to open. Use separate sessions for different students or small groups.
Read, discuss and build vocabulary
Choose a reading by topic and estimated CEFR level, from A2 to C2. Share the article before class, explore its vocabulary and comprehension questions together, then use the story for speaking or writing practice.
Plan your next lesson
Find lesson-planning guides, speaking activities and practical classroom tasks. Share grammar explanations and study tips with students for preparation, revision or independent learning.
Connect the app and your teaching
Students can practise translation, grammar, listening and writing in the Android app or on the website. Use Share with Teacher / Classroom to connect your group, review shared work and choose what to practise next.
Share a reading or a blog explanation that matches your students’ level and goals.
Discuss the topic and use Live Lesson exercises to practise together.
Set follow-up practice in the app or browser, then review the work students share.
Live Lessons run on the website. Classroom / Share with Teacher is available in both the Android app and the browser. Students can join your Live Lesson with a free account.
Every aspect of language learning, covered.
Grammar feedback supports 52 native languages. Website language options stay limited to reviewed translations.
Poly comes from the Greek polys, meaning many. Puff suggests a small, soft cloud, like an internet cloud for language practice. Together, Poly-Puff means many languages and ideas gathered in one light place to learn.
Download the app - free to start.
Silent video showing the Poly-Puff practice hub, translation feedback and progress tracking alongside illustrative footage of people using phones.
Start learning English for free today.
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