Privacy Policy
Overview
Last updated: October 10, 2026
Kaketa has no account and no analytics. Your practice progress and the words you add stay on your device and in your own iCloud. The handwriting check is the one feature that sends anything off your device: when you tap Check, a picture of your handwriting goes through a small server to OpenAI, as described below.
Data the app handles
- Which words you have marked known or learning, and the review schedule and counts for each.
- The words you add under My Words.
- Your settings, such as the prompt and the meaning language.
- If you turn on the attempt log: a picture of each word you wrote, with its verdict and your decision.
What you draw on the practice grid is kept only for the current card and is discarded when you move on, unless the attempt log is on.
Storage and sync
Progress, My Words, and settings are stored on your device. Progress and My Words also sync through iCloud, in your private iCloud database, between devices signed in to the same Apple Account. Apple handles that storage under its own terms; we cannot read it.
Attempt log (optional)
Off unless you turn it on in Settings. With it on, Kaketa keeps a record of each word you write: the picture of your strokes, the word, OpenAI’s verdict if you checked, and whether you chose Got It, Not Yet, or already mastered. The record is stored on your device and in your private iCloud database, like your progress, and is shown on each word’s page. It is not sent anywhere. You can delete it all at any time in Settings → Attempt Log.
Handwriting check
When the handwriting check is on and you tap Check, Kaketa sends a PNG image of what you drew on the grid and the word you were asked to write (its spelling, reading, and meaning) to Kaketa’s check server, a small service run by Kaketa’s developer on Cloudflare. The server passes them to OpenAI’s Decisions API and returns one of three answers: correct, close, or wrong. Nothing is sent unless you tap Check.
The server stores nothing about a check: not the image, not the word, and not the answer. It keeps only a count of checks per device for the daily allowance (300 a day) and a monthly total, plus the public key Apple’s App Attest gives your copy of the app, which proves requests come from the real app.
OpenAI receives the image and the word and processes them under its API terms and privacy policy. Under those terms, OpenAI may retain API inputs and outputs for up to 30 days to monitor for abuse, after which they are deleted, and does not use API data to train its models. OpenAI describes its data controls here.
No data collection, sharing, or tracking by the app
Kaketa does not transmit app data to us, collect it on a server, share it with third parties, or track you across apps and websites. The app sends no analytics to us. Apple gives us aggregated App Store statistics, and, if you have turned on Share With App Developers in iOS Settings, aggregated usage figures and crash reports; these come from Apple and do not identify you. The kaketa.jp website does not track which links you click.