Otriva

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  Circle a line in your own handwriting: the otter's explanation sits right next to it and stays on the page.

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  Quiz me: before a test, Otriva covers a spot in your own notes.

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  Once through the page: you see what has really stuck.

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  Reveal it and say whether you knew it.

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  Otriva Plus via RevenueCat: writing stays free, Plus adds more answers from the otter.

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  Subjects are binders on a shelf, just like at school.

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  iPhone companion: your notes and timetable on the way to school.

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  App icon

Inspiration

It started in a café. I was working, and my best friend Robert was studying for school. Every few minutes he complained: he was stuck on something in his notes, so he switched from Notability to ChatGPT, explained the whole context again, copied the answer back, and by the time he returned to his page he had lost the thread. One app to write, another to understand, and constant switching in between.

So I built the help into the page. Robert now studies with Otriva: he gets noticeably more done, and he stays on the topic instead of drifting between apps. A few weeks after that afternoon, the first version was in the App Store.

What it does

Otriva is a handwritten notebook for iPad and Apple Pencil, organised like the binders students already carry. On top of it sit three things that keep you on your own page:

1. Circle to understand. Stuck on a line the evening before a test? Tap "Otter helps" and circle it. The circle is the question. The explanation appears on a card right next to your handwriting, and it stays on the page like a sticky note, so it is there the next time you study. No copying, no new chat, no explaining the context again.

2. Help in your own language. Many students learn in German while German is not their first language. Circle a word and get it in your help language with article, short explanation and pronunciation; circle a sentence and get the explanation in one of 15 languages, from Arabic and Ukrainian to Turkish, Dari and Kurdish, with the German right underneath. You keep up with the lesson instead of falling behind on the language.

3. Quiz me on your own notes. Before a test, Otriva covers parts of your own page. You recall, reveal and judge yourself, so you know what has really stuck. You practise with what you wrote in class, not with someone else's flashcards. It runs on the device, no AI needed.

The effect: one place instead of two apps, no lost context, and the help is saved exactly where you will study again. Otriva runs in English and German.

How I built it

SwiftUI, PencilKit and SwiftData with private iCloud sync. Handwriting recognition runs on device. AI requests go through my own Cloudflare Worker relay, which verifies every device with App Attest and never sees an account, because Otriva has none. The RevenueCat SDK handles purchase and restore of the monthly Otriva Plus subscription; the relay counts delivered answers per subscription period.

Challenges

• AI that stays in Europe, and it is still open. Our users are school students, so their questions should be processed inside the EU. I tested the providers one by one: several "EU" endpoints route requests wherever capacity is free, and the ones that truly guarantee EU processing were too slow, too weak on school topics, or need an enterprise contract. EU processing at the quality, speed and price a student app needs is still work in progress.
• Undo on a full page used 34 MB. A handwritten page holds a lot of ink. I rebuilt the history to store stroke differences instead of page copies: 0.14 MB, pixel-identical after undo.

Accomplishments

• Seven App Store releases in the first month, built by one developer.
• Otriva started in classes at IGS Linden, a school in Germany.
• Robert studies in one app now, and stays on the topic.

What's next

• A real learning path. Today Otriva helps you understand your notes. Next it helps you learn them: real lessons built from your own handwriting, interactive, and hard enough to challenge you.
• Speaking up in class. For students learning German: practise putting your own thoughts into German, so you can take part in the lesson, not just follow it.
• From IGS Linden to Europe, and to the iPhone, with AI processing that stays inside the EU.

Built With

• app-attest
• cloudflare-workers
• cloudkit
• pencilkit
• revenuecat
• swift
• swiftdata
• swiftui
• typescript