Upload a Spanish EPUB — get instant English vocabulary glosses
Our AI annotator highlights new Spanish vocabulary with natural English glosses while preserving the original EPUB layout. Learn faster with CEFR-aware filtering, zero copy-paste lookups, and a clear credit counter (your first three conversions are free).
Perfect for Spanish learners, translators, and ebook enthusiasts—no software install, start free now.
Every annotation consumes one of your three complimentary credits; once they’re gone you’ll need to recharge with pay-as-you-go credits or switch to an unlimited subscription.
✔ Your account includes 3 free conversions; the counter updates after every upload.
Want the full breakdown? Explore how credits & pricing work or read the workflow guide.
Two simple steps: upload & download
🎁 Free plan includes three conversions. The banner inside the form shows exactly how many free credits remain before you need to top up.
Average processing time
15s
Annotate a full EPUB in one pass
Vocabulary covered
10k+
Common words filtered, rare terms highlighted
Export format
EPUB 3
Tested with Apple Books, Kindle, KOReader
Why learners and publishers trust this workflow
From vocabulary discovery to final delivery, the assistant helps you read Spanish originals without sacrificing English comprehension or EPUB fidelity.
Smart frequency filtering
Set the CEFR level you already master; the assistant skips those words and glosses vocabulary that falls above your chosen band.
Hybrid translation sources
Starts with a curated glossary, then falls back to LibreTranslate or MyMemory to deliver complete English glosses.
Ephemeral processing
Files stay in memory only; once the annotated EPUB is generated it is immediately available for download and discarded.
Reader-friendly markup
Uses native <ruby> tags so bilingual annotations render cleanly on modern EPUB readers without breaking layout.
Configurable translation backend
Bring your own LibreTranslate endpoint and API key for faster, private lookups that suit team deployments.
Flexible pricing after trial
Sign in to unlock three free conversions, then continue with pay-as-you-go credits or unlimited monthly/yearly plans.
Learning insights
Summarises annotated vocabulary counts so you can track book difficulty and plan study sessions.
Annotate an entire book in three steps
Powered by the EPUB standard and multiple translation layers, this pipeline keeps your source structure intact while surfacing actionable study data.
Upload the original EPUB
Supports standards-compliant EPUB files from major publishers. We extract only the text content in memory.
Detect and translate new words
Applies CEFR-aware filtering, stop-word checks, and translation fallbacks to retrieve natural English glosses.
Download the annotated edition
Injects glosses as <ruby> annotations, repackages the EPUB, and delivers a ready-to-read download instantly.
Sample snippet (after annotation)
El viajero miró el paisaje con una mezcla de nostalgia y esperanza, listo para comenzar un nuevo capítulo.
* Example for illustration purposes; translations come from the glossary and translation providers you configure.
Trusted by teachers, learners, and publishers
Hear how the assistant streamlines bilingual reading across classrooms, personal study, and editorial pipelines.
“My students used to spend class time looking up every other word. Preparing the annotated version in advance cuts lesson prep by at least 30%.”
Lucía Martínez
Spanish teacher, Madrid
“The ruby glosses show up on every device and pair perfectly with Anki reviews. It finally made full-length Spanish novels approachable.”
Alex Chen
Independent learner, New York
“Our multilingual team now generates bilingual review copies in minutes. It replaced a tedious manual workflow.”
Marta Gómez
Publishing localisation consultant
Frequently asked questions
Still curious? Reach out via the contact email in the footer.
Do you store the uploaded EPUB?+
No. The file is unzipped, annotated, and repackaged entirely in volatile memory. Once the download is ready, the temporary data is destroyed.
Where do the English translations come from?+
We prioritise our curated glossary, then fall back to the LibreTranslate endpoint you configure, and finally the public MyMemory API if needed.
How large can the EPUB be?+
Uploads up to roughly 30 MB work best. Larger volumes may take longer to process, so consider splitting very large compilations.
Will Kindle or Apple Books render the glosses?+
Yes. The output is standard EPUB 3 with native <ruby> elements, tested on Kindle Scribe, KOReader, Apple Books, and Thorium.
Can I batch process multiple books?+
The web app handles one book at a time. For classrooms or publishers, contact us to explore API-based batch processing.
Ready to dive into your next Spanish original?
Upload now to receive a fully annotated EPUB in seconds. Perfect for classrooms, self-learners, and localisation teams alike.
Each account includes three free conversions; afterward you can top up for $4.90 per book or unlock unlimited access for $9.90/month or $49.90/year.