DualBook 8 languages

Free online tool — no sign-up

Make a Portuguese-French bilingual book

Each Portuguese paragraph with its French translation directly beneath it, in one EPUB. Read the Portuguese first; the French is there to catch the sentence you half-understood.

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

Portuguese and French are the two major Romance languages that nasalise their vowels, and they share a great deal of vocabulary besides — which means a Portuguese reader gets further into a French page than they expect and then trips on something specific. The trouble is never knowing which something. A translation directly underneath answers that in a glance instead of three dictionary lookups.

It also shows the punctuation working differently. Portuguese opens speech with a dash and runs on; French closes it in guillemets. Seeing both on the same screen makes a convention visible that you would otherwise absorb slowly and wrongly.

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

How it works

  1. Choose a Portuguese EPUB

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

  2. The model reads the whole book

    Names, terms and the formal/familiar map are fixed once, so the French keeps its footing across chapters.

  3. French is inserted under each paragraph

    Each translation is styled beneath its paragraph, distinguishable at a glance even though the two languages look similar.

  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

Read the Portuguese first, then check. With related languages the half-right reading feels identical to the right one, and only the second version tells you which you had.

Fifteen pages get translations. The rest of the book stays in Portuguese 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?

Portuguese first, and check rather than glance — the checking is where the value sits.

Is the French punctuated the French way?

Yes: guillemets and dialogue dashes rather than the Portuguese convention, which makes the difference between the two systems visible on every page of dialogue.

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