| Hi HN! I built *BookTranslator.app* (https://www.booktranslator.app/) initially to help myself read English books in my native language. Later on as I shared on twitter, more and more people were finding it useful. So I thought it might also be helpful to share it here. You can drag-and-drop an *EPUB or PDF (≤ 50 MB)*, pick one of *76 target languages*, and ~60 seconds later you get a layout-preserving translation plus a side-by-side bilingual reader. The whole pipeline runs on the gpt-4o API with a bit of prompt-engineering to keep chapter structure, images and footnotes intact. ### Why I think it’s worth showing * Most “AI translators” still force you to split books into chapters or plain text; I wanted true *one-click, whole-file* handling.
* Speed: 100k words finishes in about a minute because translation requests are parallelised at the section level.
* The bilingual view has proven handy for language learners and volunteer proof-readers. ### Tech stack * *Frontend*: Next.js + Tailwind.
* *Backend*: Node.js with GPT-4o calls ### Try it (no signup)
There’s a *guest tier* without needing for signup and a *free tier)) providing 1,000 free credits so you can upload a small chapter or novella. Full pricing starts at a \$10/mo Pro plan. ### Looking for feedback
1. Accuracy vs. speed trade-offs – would you prefer a slower “highest-quality” model option?
2. Does the side-by-side reader help, or would you rather download just the translated EPUB/PDF?
3. Any edge cases (RTL languages, math formulas, EPUB3 media overlays) I should prioritise? ### Caveats & next steps
* Still ironing out rare formatting glitches (tables, SVG images). Thanks for reading—happy to answer anything! |