DualBook 8 languages

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Make a Spanish-Portuguese bilingual book

Each Spanish paragraph with its Portuguese translation directly beneath it, in one EPUB. For the closest pair in this catalogue, the parallel form is a correction tool rather than a crutch.

The first 15 pages of text are sent to our server to be translated. The file itself stays on your device.

If you read Spanish you can already read most Portuguese, and that is precisely the problem. Comprehension is not what you are missing; accuracy is. The words that are not what they look like, the constructions that diverge, the pronoun system that behaves differently — none of those announce themselves, and without a second version in front of you there is no mechanism by which you would ever discover you had them wrong.

Stacked paragraphs supply that mechanism at almost no cost in reading time, because you are reading both languages at nearly full speed anyway.

Your browser opens the EPUB, walks each paragraph and inserts the Portuguese beneath it inside the original file, rewriting only the chapter documents that received a translation.

How it works

  1. Choose a Spanish EPUB

    A DRM-free EPUB. The bilingual file is assembled in your browser, not on a server.

  2. The model reads the whole book

    The variety of Portuguese and the names are fixed once, so the translation does not change dialect between chapters.

  3. Portuguese is inserted under each paragraph

    Each translation is styled beneath its paragraph — styling that matters more here than anywhere, because the two languages look alike on the page.

  4. Read it here, or on any device

    A complete EPUB carrying the book's own fonts and stylesheets.

The trap, and the honest limits

The two blocks look similar. That is a property of the pair, and the reason the translated paragraph is set smaller, in a different colour, with a rule down its edge.

Skimming defeats the purpose. Read the Spanish, decide what you think it says, then check — the value here is entirely in the checking.

Fifteen pages get translations. The rest of the book stays in Spanish inside the same file.

The text is sent to a server and discarded when the job ends. The file never leaves your device.

Questions

Which side should I read first?

Spanish first, and check rather than glance. With languages this close the gain is in catching the small divergences, not in understanding the page.

Is this useful when I can already read both?

That is exactly the case for it. When comprehension is not the problem, precision is — and the only way to find out which cognates you have been getting wrong for years is to see both versions side by side, repeatedly.

How do I tell the two blocks apart?

The translated paragraph is smaller, in a different colour, with a rule down its edge. That distinction does more work in this pair than in any other.

Will it open on a Kindle?

Yes. Kindle has accepted EPUB directly since 2022; email the file to your device or copy it across.

The whole book, in parallel

The app builds the bilingual version of the entire book, with tap-to-look-up and your reading position synced across devices.

Open DualBook