Read your own EPUB with translation
Upload an English EPUB of up to 30 MB, or paste any English text, and Booklern turns it into a bilingual book: the English on the page with a translation under every sentence, natural audio, a tap-to-look-up dictionary and one-tap vocabulary saving. The book is visible only to your account.
What you can upload
EPUB files without copy protection, up to 30 MB, in English. PDF is not supported: a PDF holds pages, not sentences, and a sentence-aligned translation needs the sentences. If your text is not in an EPUB, paste it as plain text and Booklern makes a book out of it.
The book must be in English. Booklern translates from English into Russian, Spanish, Brazilian Portuguese, Japanese, Chinese, Turkish or Arabic; it does not translate the other way round.
What happens after you upload
The EPUB is split into chapters and sentences and appears in your library within a minute. Nothing is translated in advance: each page is translated the first time you open it, sentence by sentence, and kept, so a page you have read once never costs a second translation.
From then on the book reads exactly like a library classic: translation under each sentence or beside it, a voice that reads the chapter aloud with the current sentence highlighted, a dictionary on every word, and a vocabulary list that collects what you save. Your place in the book is kept across devices.
Privacy and limits
Uploaded books are private: nobody else can see them, and they never enter the public library. The text is sent to the translation and speech services to provide those features and to nothing else.
Upload needs a free account. Translation, audio and pronunciation checks have a fair-use daily allowance while Booklern is in early access; reading pages that are already translated is always unlimited.
Why translate a book sentence by sentence
A translated file read on its own teaches you nothing about the English. A whole-book machine translation read side by side drifts out of step within a page. Sentence alignment keeps the two texts locked together, so you can read the English and check a single sentence without hunting for it. The guide Learn words from context shows how to use that while reading.
