Sloth Reader · Read slow, understand deep

Read any book in thelanguage you're learning

An e-book reader for language learners: it reads aloud, explains the words you tap, and keeps them for review.

Chapter Three · the sentence you are hearing

Reading in a new language should feel like an adventure, not a vocabulary test.

The app's default voice, streamed from this page. On your phone, it runs on the phone.

A novel open in Sloth Reader: sepia page, serif type, a thin progress line at the foot.
The listening panel: a sloth reading, an amber karaoke line, speed and sleep-timer chips.
A tapped word opened as a small card: pronunciation, meaning, a save button.

Read, listen, remember

Read.

Your own EPUBs, set the way a book should be: serif type, real margins, four reading themes, highlights that stay where you put them. No store, no lock-in. The books are yours.

The typography panel: font choices, size and spacing sliders, four page themes.

Listen.

A natural voice reads along, highlighting each sentence like a karaoke line. Screen off, AirPods in, it keeps your place, and your books never leave the phone.

The listening panel over a page: play, speed, sleep timer.

Remember.

Every word you tap is saved with its sentence and its book. Spaced repetition brings them back on the right day, and Anki export is one tap away.

A word card with meaning, pronunciation and a save action.

Reading in a new language should feel like an adventure, not a vocabulary test.

Kokoro, neural and on-device, the default

Hear the difference

One sentence, three voices. The first is what most reading apps still give you. The last is Kokoro, running entirely on the device: no cloud, no per-minute cost, works on a plane. Kokoro-82M · neural · on-device

From page to vocabulary

Nothing to set up, nothing to migrate. Bring the book you already meant to read; the habit builds itself around it.

Evening

Import your bookone minute
Read a chaptertwenty minutes
Tap the words you don't knowas they come

The commute

Listen, screen offforty minutes
Karaoke keeps your placehands free

Some evening soon

Review what you savedfive minutes
One book laterthree hundred words, yours

Sloth Premium

  • Reading, free forever
  • Every voice, every language
  • Bilingual pages & sync
  • Spaced review, unlimited
  • Anki export
  • Works fully offline

No cloud required, no per-minute voice costs. Early-access members keep the lifetime launch deal.

$39.99

per year · cancel anytime

Get early access

Questions

Which languages? At launch: books in English with dictionaries for Vietnamese, Japanese, Korean, Chinese and Spanish, plus an English–English dictionary. Voices for English and Vietnamese first; Japanese, Korean, Chinese, Spanish, French and Italian follow, each downloading on demand.

Where do the books come from? You bring your own: EPUB, TXT, Markdown and text-based PDF, imported from Files, the share sheet or WebDAV. There is no store, and we never touch DRM-locked books.

Does it work offline? Entirely. Voice, translation and dictionary all run on the device. You need the network once, to download a voice and a dictionary; after that, a plane is a reading room.

What does it cost? Reading is free forever: full reader, one voice, a hundred saved words. Premium at $39.99 a year covers every voice and language, unlimited spaced review, bilingual pages, sync and Anki export. That's a third of what the big TTS apps charge, because our voices cost us nothing to run.

What about my privacy? Your books never leave your phone. Nothing you read, tap or save is uploaded; the pipeline that pronounces and translates runs on the device. Cloud features exist, off by default, and use your own key if you ever turn them on.

Android? iOS first: iPhone and iPad in one app. Android will be considered seriously once the iOS version is loved.

When can I try it? The iPhone beta opens soon; the waitlist below goes in first, in order, and keeps the lifetime launch deal.

Who makes this? Santaris, a small team that reads slowly and believes a language is learned one page at a time.

Let the words stay

You already read. Read in the language you're learning, and Sloth keeps every word you meet. Three minutes of questions shape what we build first and put you at the front of the beta with the lifetime launch deal.

Or just leave your email; one message when the beta opens, nothing else.

You're on the list — thank you. Check your inbox.

An 1849 wood engraving of a stork from Anthony Rich's Illustrated Companion to the Latin Dictionary.