Memory you control
Koishi may suggest a note worth remembering, like a name or something you're working on. It's saved only if you approve, and you can edit or delete any note at any time.
小石 · koishi · a little pebble
A little pebble that listens.
Koishi asks how you are, listens, and answers warmly and briefly. Vent, untangle a thought, or send a stone when words are hard.
How was your day, really?
Koishi is an AI, not a person.
Stones
No words? Send a stone.
Ten hand-drawn stones for the days typing feels like too much. Koishi answers the feeling behind it. Try one.
How are you feeling right now? You can send a stone.
Example replies. In the app, Koishi writes a new one each time, in your language.
How it works
It asks first. You answer.
Small on purpose
Everything you need to say how you are.
My week in colours
A mood calendar that lives on your iPhone and keeps colours and emoji only. Turn your week into a colour card to share. It never includes what you wrote.
Gentle follow-ups
Pick a note, and Koishi can check in later to ask how it went.
Big presentation on ThursdayCheck in Friday, 9:00
On your Home Screen
Keep Koishi on your Home Screen in the colour of your last mood, and log how you feel with one tap.
Speaks your language
Koishi replies in the language you write in.
- English
- Español
- Português
- Deutsch
- Français
- 日本語
- Türkçe
Privacy
Your chats live on your iPhone.
Koishi is built to need as little as possible. Here is exactly what happens to what you write.
Read the privacy policy- Stored on your iPhone. Your conversations, drafts and notes are kept on your device. You can export or erase them in Settings.
- Sent only to write a reply. Your message, recent context and the notes you've allowed go through our server to an AI provider. We request zero data retention on every model call.
- Notes need your yes. Koishi only remembers what you approve, and you can change your mind any time.
- No ads, no trackers. No advertising trackers in the app, and this website sets no cookies and runs no analytics.
- Leave whenever you like. Delete your account from Settings and our server account goes with it.
Honest by design
What Koishi is, and isn't.
Koishi is
- A small AI companion for adults, 18 and over
- A place to vent, think out loud or untangle your day
- Clear that it's an AI, and that its replies can be wrong
Koishi isn't
- A person or a replacement for the people in your life
- A therapist, or a medical or emergency service
- Able to diagnose, treat or send help
If you might be in danger, call your local emergency number now. In the US, call or text 988. Elsewhere, find a helpline at findahelpline.com. Koishi shows crisis resources when they may help. How Koishi responds to crisis messages
Plans
Start free. Go Plus for more.
Free
A few AI replies every day
Talk, send stones, keep notes and fill your week with colour.
Koishi Plus
Up to 1,000 replies a month
An optional monthly subscription. You'll see the price in your currency before you buy, and you can cancel any time in your Apple Account.
FAQ
Questions, answered.
Is Koishi a therapist?
No. Koishi is an AI companion for everyday thoughts and feelings. It isn't a person, a therapist, or a medical or emergency service, and it doesn't diagnose or treat anything. If you might be in danger, contact your local emergency number or someone you trust.
Where are my conversations stored?
On your iPhone. To write a reply, the message you send, recent context and any notes you've allowed are sent through our server to a third-party AI provider. The privacy policy lists every party involved.
Why "Koishi"?
小石 (koishi) is Japanese for "pebble", and that's what Koishi is: a tiny friend made of pebbles.
Which languages does it speak?
English, Spanish, Portuguese, German, French, Japanese and Turkish. The app itself is translated into all seven.
How much does it cost?
Koishi is free to download and includes a few AI replies every day. Koishi Plus is an optional monthly subscription with a much larger reply allowance. Payment goes through your Apple Account and renews each month unless you cancel at least 24 hours before the period ends.
How do I delete my data?
In Settings you can erase chats on your iPhone, edit or delete notes, withdraw consent for AI processing, or delete your account. Deleting your account removes it from our server. It doesn't cancel an Apple subscription, which you manage in your Apple Account.
Say hello to Koishi.
It's already wondering how your day went.
Download on theApp Store
Coming soon to theApp Store