Your AI language mentor, right on the page

Read a book. Get to know a language.

Read a book in the language you're learning. Ask Tobien why a verb changes, what an expression means, or how to say it another way. Get clear explanations, ask follow-up questions, and practice with words from your book.

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Books you chooseExplanations as you readPractice from your books

The Metamorphosis

Franz Kafka · Chapter I

Excerpt 1 / 3

… fand er sich in seinem zu einem ungeheueren .

verwandelt

verwandelnto transform

Past participle · Partizip II

/fɛɐ̯ˈvandl̩t/

Verb · resulting state

In this sentence

He finds himself already transformed. Verwandelt describes his new state: the change has happened before he becomes aware of it.

Natural translation

… in his bed, he found himself transformed into a monstrous creature.

Word for word

… found he himself in his bed into a monstrous vermin transformed.

Words in context

Bettbed
Ungeziefervermin
verwandeltto transform

How the sentence works

sich + Zustand + finden

Fand er sich means “he found himself”. Fand is the past tense of finden, and sich refers back to er, “he”. Verwandelt describes the state he discovers himself in. The phrase with zu tells us what he has become.

Why this wording matters

Why translate Ungeziefer as “creature”? The German word conveys disgust but leaves the kind of creature unclear. “Vermin” captures that unpleasant feeling; “creature” reads more naturally here. Neither carries every shade of the original.

Tap a word, then ask the AI mentor. This demo uses prepared answers. In the app, you can ask your own questions about your book.

Why I built Tobien

I wanted to understand the Spanish I was reading.

When I moved to Spain, I didn't speak Spanish. People kept telling me to read books, and I liked the idea of learning through a good story. Looking up words helped me follow along, but I still had questions. Why this tense? Why that preposition? Could you say it another way? I wanted an app that would help me work it out.

That's why I built Tobien. You choose the book, and an AI mentor helps you explore the language in it. You can ask about grammar, compare expressions, and keep asking when something isn't clear. I wanted those explanations alongside the text. It's still how I learn Spanish today.

Todo bien.VadimFounder of Tobien. Still learning Spanish.

Vadim, founder of Tobien

The Metamorphosis

Franz Kafka · Chapter I

Excerpt 1 / 3

… fand er sich in seinem zu einem ungeheueren .

verwandelt

verwandelnto transform

Past participle · Partizip II

/fɛɐ̯ˈvandl̩t/

Verb · resulting state

In this sentence

He finds himself already transformed. Verwandelt describes his new state: the change has happened before he becomes aware of it.

Natural translation

… in his bed, he found himself transformed into a monstrous creature.

Word for word

… found he himself in his bed into a monstrous vermin transformed.

Words in context

Bettbed
Ungeziefervermin
verwandeltto transform

How the sentence works

sich + Zustand + finden

Fand er sich means “he found himself”. Fand is the past tense of finden, and sich refers back to er, “he”. Verwandelt describes the state he discovers himself in. The phrase with zu tells us what he has become.

Why this wording matters

Why translate Ungeziefer as “creature”? The German word conveys disgust but leaves the kind of creature unclear. “Vermin” captures that unpleasant feeling; “creature” reads more naturally here. Neither carries every shade of the original.

Let your reading lead the way

Read, ask, and put it into practice.

Pause at a sentence that catches your attention. Explore its meaning, ask the mentor about a tricky detail, then practice the words you've just met. Pick up the story whenever you're ready.

Give a tricky sentence your full attention.

Work through a passage one sentence at a time. Explore the words and how they fit together, then move on when you are ready. Nearby lines keep the wider passage in view.

Try the different views and tap a word. You can explore the demo right here.

Words in context

See what a word means here.

Meaning, form, and context

See what the word means in your sentence, find its dictionary form, and understand the grammar behind the form you're reading. Keep the sentence in view as you explore.

Hear how it's pronounced

Listen to the word and check its phonetic transcription. Connect the spelling on the page with the sound you'll hear in conversation.

Build your own vocabulary

Mark the words you know, the ones you're learning, and those you'd like to skip. Find them in your personal vocabulary, with highlights in the book to help you spot them again.

For all your language questions

Find out why it's said that way.

Explore a tricky tense, compare similar words, or find out what sounds natural with a friend. Your AI mentor explains the language in your passage, and you can keep asking for examples or a simpler explanation.

Explore grammar and expressions in the passage you're reading
Ask follow-up questions and return to saved conversations
Type your question or dictate it

Pro and Ultimate include access to the advanced AI mentor. Switch between Standard AI and Advanced AI in the app settings.

Standard includes 100 AI credits a month; Pro includes 300. Ultimate has a fair use limit of 2,500 credits per monthly subscription period. See AI usage limits.

Try the AI mentor

See what one sentence can teach you.

Disculpe, no entiendo lo que me ha dicho.

A past action that matters now

Ha dicho means “you have said” here. What was said still matters because the speaker is trying to understand it now. Ha comes from the helping verb haber, and dicho is the irregular past participle of decir. The speaker is using the polite usted form, so it is ha dicho. With a friend you address as tú, it would be has dicho.

Choose a question to see an example explanation. These answers are prepared for the demo. In the app, the mentor responds to your questions about your reading.

Follow your interests

Start with a book you can't wait to read.

Bring a favorite, try a classic, or tackle something a little more challenging. Tobien helps with the language as you go and saves your place for next time.

EPUBPDFDOCX / DOCTXT / RTFFB2HTML / Markdown

Your books stay together in your personal library.

Bring your own books

Upload a file in a supported format, then start reading and exploring the language. For PDFs, move through the book one page at a time.

Find your next read

Browse Project Gutenberg, Wikisource, and OAPEN by language and level. Find a book that catches your eye and add it to your library.

Get a feel for the vocabulary

94%familiar words

This example estimates that 94% of the words are already in your vocabulary. Use it as a guide to choose a comfortable read or try something more challenging.

Build on what you read

Turn words you've read into words you know.

Practice with words from your book

Choose a meaning, complete a word form, type an answer, or put a sentence together. Exercises use vocabulary from your reading, and your answers help shape what comes next.

4 exercise formats

Take your practice offline

Revisit the words you're learning and use the explanations to understand your answers. Download a practice pack ahead of time to keep reviewing without an internet connection.

Offline review

See your reading add up

Track your reading time and the words you know. Set a daily goal that works for you and build a reading habit at your own pace.

Learn at your own pace

Settle in with a good book

Make yourself comfortable.

Choose a light or dark theme, adjust the text size, and set the spacing between lines. Read a full page or slow down with one sentence at a time.

Pick a theme to see how the text and explanations will look.

Spot the words you're learning.

Disculpe, no entiendo lo que me ha dicho.

NewLearningKnown

Subtle highlights help you tell new words apart from the ones you're already learning.

Books in six languages

Which language will you read next?

Choose the language you're learning and bring a book that interests you. The app's menus and explanations are available in English and Russian.

  • English
  • Spanish
  • German
  • French
  • Italian
  • Russian

Your book. Your questions. Your AI mentor.

Start with the book you've been meaning to read.

Let the story pull you in. When the language gets tricky, ask Tobien to explain. Each chapter gives you new words, useful patterns, and something to practice.

Try Tobien for free

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