A reader built for language learners.
I wanted to learn a new word without leaving the page, and to capture or share a thought the moment a passage connects with me. So I built Casu, and it has become my everyday reader.
Select a word. Its meaning appears in your language.
Pick the language your definitions come in, and every word you select shows its meaning right on the page, with an English definition and audio. The word stays underlined in gold and joins your New Words list.
Marked by heated arguments or controversy.
Everything you read, in one place.
Add a PDF, EPUB or plain text file, or paste a link to an article or RSS feed. You can also save straight from Safari's Share menu. Casu can combine related RSS articles into a book.
A page that feels like a page.
Pages turn with a real curl. Choose Paper, Sepia, Night or E-Ink, set it in Garamond, Georgia, Palatino or 宋体, and pick a page clip color. Listen whenever your eyes need a rest: Casu reads everything aloud in natural voices.
Catch the line. Keep the thought.
Highlight a passage and the gold page clip brings you back to where you were in one tap. Turn a highlight into a card in Light, Dark or Serif style, then save it to Photos or share it with your club. When a passage sets you thinking, start a Spark: type it, or write it by hand.
Your highlights, your new words, and a companion.
Collect gathers your highlights and new words from the book. Tap any of them to jump to its passage. The Companion answers questions about what you're reading, recaps where you are, and suggests questions. It runs on Apple Intelligence: private, with no sign-in.
Passages that came back.
Every week, Casu brings back passages from your reading a month or more ago, arriving again on their own time, with translations where you need them. It's spaced review for the lines that mattered.
"From your reading a month or more ago, arriving again on their own time."
Reading is personal, but thoughts want to socialize.
A Circle is a book club that keeps friends on the same chapter. Set a schedule of sessions, plan a meetup, and post to the feed. Friends can answer with "Me too" or "Say more".
- Offline. Everything outside your Circles works without a connection.
- No tracking. What you read and look up stays with you.
- E-Ink. A theme made for e-ink screens.
Questions
What can Casu open?
EPUB and PDF files, plain text, web articles and RSS feeds. You can add files or paste a link, or save from the Share menu in Safari. Casu can also combine related RSS articles into a book.
How does Casu help language learners?
Select any word and its meaning appears on the page in the language you choose, with an English definition and audio. The word is underlined and saved to your New Words list, and your weekly Reading Brief brings back passages from a month or more ago.
Can Casu read books aloud?
Yes. Casu reads everything aloud in natural voices, so you can listen and follow along on the page.
Does Casu work offline, and does it track me?
Everything outside Circles, the book club, works offline, and there is no tracking. The reading Companion runs on Apple Intelligence: private, with no sign-in.
Is Casu available?
Casu is coming soon to iPhone.
Read the language you're learning. Keep every word.
Books, PDFs, articles and feeds, with meanings in your own language. Casu is coming soon to iPhone.