Cangjie
The native key layout, with every keycap showing its English letter and its Cangjie radical together. Candidates are ordered by frequency, and the characters you pick often move towards the front.
KOI Keyboard
A Chinese keyboard built for Hong Kong
Cangjie, Quick, Stroke, Jyutping, Zhuyin — five input methods sharing one keyboard.
Handwriting runs on the device. The typing engine has no networking code at all.
Preparing for releaseKOI is being prepared for App Store review. A download link will replace this notice once it is live.
Five input methods, one keyboard
No more cycling through the system keyboard list just to change input method. All five modes live inside KOI and switch instantly.
Quick
First-and-last-code input. It shares the Cangjie key layout, so there are no new key positions to learn.
Stroke
Five-key stroke input with * as a wildcard — forget a stroke in the middle and a star still finds the character.
Jyutping
Full and abbreviated spellings both work, and a tone number narrows the results. Outputs Hong Kong Traditional Chinese.
Zhuyin (Dachen)
A dedicated Zhuyin key layout that outputs Taiwan Traditional Chinese.
English
The same keystrokes are decoded into Chinese and English candidates at once, so typing English needs no keyboard switch. Disabled in Stroke mode.
Actual screens
Both of these are captures of KOI running. Neither is a mock-up.
Actual capture
Actual capture
Type however you like
Four ways of entering a code can be mixed inside a single composition. Change your mind halfway through and you do not have to clear it and start again.
Tap, glide, mix, two-finger chord
Tap key by key, glide through the whole code in one stroke, or start tapping and finish gliding. Two fingers pressing at once are picked up as well. It all folds into the same composition.
A glide that drifts still lands
Glide decoding tolerates up to two keys being substituted by a neighbouring key. A finger that wanders slightly does not derail the input.
A wrong code never leaves you with nothing
When you decompose a character wrongly, KOI fills in candidates from near-miss codes and places them after the normal ones. The candidate row never goes blank while you wait.
Delete and cursor
One press deletes the last code, two presses clear the whole composition, and holding it down accelerates. Swipe left or right on the space bar to move the cursor.
Handwriting, with nothing to connect to
The handwriting recognition model is packaged inside the app. Nothing to download, nothing to connect to, and it writes just as well in aeroplane mode.
A Hong Kong handwriting model
KOI uses a Hong Kong Traditional Chinese handwriting model, not a Mandarin or Simplified one. The character shapes you are used to writing are the ones it recognises.
Ink on water
The handwriting area is rendered in Metal as a pool of water: your strokes leave ripples, refraction and waves. The intensity is adjustable in settings, so turn it down if you prefer it still.
KOI Agent
Open it when you need it; leave it closed and it is simply not there. Six modes, all handled on the keyboard, without jumping out to another app.
Auto
Reads what you have in front of you and decides what to do.
Ask
Ask directly, and insert the answer straight into the field.
Reply
Draft a reply to the message you received.
Rewrite
Polish, change the tone, translate.
Sticker
Generate a sticker with a transparent background.
Image
Generate a full scene image.
What each AI action costs
Credits are spent only when you ask KOI Agent to do something. Everyday typing, candidates and handwriting recognition never cost Credits.
| Action | Credits |
|---|---|
| Reply suggestion | 1 |
| Rewrite and polish | 1 |
| Translate | 1 |
| Ask a question | 2 |
| Generate a sticker | 6 |
| Generate an image | 18 |
The typing engine has no networking code
KOI's input engine — candidate generation, code decomposition, learning history — contains no networking code at all. What you type does not leave your device.
Text goes out in exactly one situation: you open KOI Agent yourself and send a request. There is no other exception.
- No analytics, no crash-reporting SDK, no advertising identifier
- No logging of the keys you press
- Learning history and custom settings stay on the device, or in a private iCloud that you control
- Full detail in the privacy policy
KOI Plus
The free version already includes all five input methods, handwriting, learning and every core typing feature. Plus adds two features, along with a monthly allowance of Credits.
Predictive input
After a character is committed, KOI suggests the next word or a whole phrase, so there are fewer characters to decompose one by one.
Cross-device sync
Settings and learning history sync through your own private iCloud. It is off by default, and once it is on you press sync yourself — nothing is sent quietly in the background.
How Credits work
- Included with a subscription
- Monthly and annual plans both grant 250 Credits each month. An annual plan releases them in twelve grants across the year rather than all at once. Each grant is valid for 60 days from the day it is issued.
- Bought separately
- Credit packs come in 100, 300 and 800. They are one-off purchases and do not expire. They do not include predictive input or cross-device sync.
- When Credits are spent
- Only when you ask KOI Agent to do something. Everyday typing does not involve Credits.
Requirements
- iOS version
- iOS 16.0 or later.
- Full Access
- The AI features and pasting from the clipboard need “Allow Full Access”. Without it, all five input methods, candidates, learning and handwriting keep working exactly as before. See the support page.
- Character coverage
- Candidates cover the Han characters in the Basic Multilingual Plane (BMP). Some extremely rare extension characters (Ext B and beyond) cannot be typed yet.
- Interface language
- The app interface is in Traditional Chinese (Hong Kong).