Every word you meet, in your own language knowledge base.

What Koboshi fixes

Finding what a word means is no longer hard. ChatGPT explains it, and dictionaries, learning apps and subtitles are everywhere. Keeping the word is the hard part. Looked-up words scatter across chat histories, notes and screenshots, cannot be found again, and fade. Koboshi gives them one place to live.

The language knowledge base idea

A search result helps for a moment and does not add up. In Koboshi, a saved word becomes one card with its meaning, examples and pronunciation, and comes back on a spaced-repetition schedule. If you use several languages, the same meaning sits side by side in each language you know, and the links between words are kept. Over time those saved words become your own language knowledge base.

Why Koboshi was made

Language tools are good at teaching, searching, explaining and practising. The useful words you meet there tend to vanish once the moment passes: lessons do not record them, chats scroll away, and flashcard apps ask you to build every card yourself. Koboshi was made to fill the gap after the encounter.

The longer version, including the moment that started it, is in Why I built Koboshi.

The name

It comes from okiagari-koboshi (起き上がり小法師), the Japanese doll that stands back up every time it falls. Forgetting a word is normal. You forget it, meet it again, recall it, and that cycle is how a word is learned. Koboshi is the tool that picks the word up again, as many times as it takes.