KOI Keyboard
Make room for your words.
Cangjie, Quick, Stroke, Jyutping and Zhuyin. Tap or glide, then keep the conversation moving.
Everyday input stays on your device. Bring in KOI Agent when you want a hand with a reply, rewrite or image.
- 5 Chinese input methods
- On-device handwriting
- Optional AI · uses Credits
iOS 16.0+Traditional Chinese · Hong Kong
One keyboard, five input methods
Choose your way to type Chinese, with English candidates alongside. Switch the Chinese input mode in the KOI app settings.
- CangjieThe native key layout, with every keycap showing its English letter and its Cangjie radical together. Candidates are ordered by frequency, and the ones you pick often move towards the front.
- QuickFirst-and-last-code input, on the same key layout as Cangjie. There are no new key positions to learn.
- StrokeFive-key stroke input with
*as a wildcard — forget a stroke in the middle and a star still finds the character. - JyutpingFull 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.
- EnglishThe same keystrokes are decoded into Chinese and English candidates at once, so typing English needs no keyboard switch.
Room for a wandering finger
Tap, glide, mix the two, chord with two fingers — all four can be mixed inside a single composition. Change your mind halfway through and you do not have to clear it and start again.
- Glides that driftDecoding tolerates up to two keys being substituted by a neighbouring key. A finger that wanders slightly does not derail the input.
- Wrong codes still landNear-miss codes can add alternatives after exact-match candidates. Check the candidate before committing it.
- Delete and cursorOne press deletes the last code, two presses clear the whole composition; swipe left or right on the space bar to move the cursor.
Make it feel like yours
Core Chinese input and handwriting are available free. KOI Plus adds prediction, appearance customization, key sizing and optional sync. Monthly and annual subscriptions include a monthly Credit allowance.
- AppearanceInkGold and Recessed are Plus-exclusive themes. Choose the look in KOI settings.
- Key sizingAdjust key height, width and row spacing to suit your hands.
- PredictionSuggestions can help continue a word or phrase after you commit a character.
- Optional syncManually sync settings and learning through your private iCloud. Requires a KOI account, iCloud and Plus; off by default.
The full subscription and Credit terms are in the terms of service; how Credits are counted is on the support page.
AI that turns up only when you ask
Draft, rewrite, translate, ask questions, or make a sticker or image without leaving the keyboard. Guest access is supported; AI needs Full Access, a connection, Credits and your consent.
- AutoUses the context shown in the preview to choose a suitable action.
- AskAsk directly, and insert the answer straight into the field.
- ReplyDraft a reply to the message you received.
- RewritePolish, change the tone, translate.
- Stickers and imagesGenerate a sticker with a transparent background, or a full scene image.
Credits are spent only when you ask for something; everyday typing, candidates and handwriting recognition never cost any. What each action costs is on the support page.
Ordinary input runs locally
KOI's input engine generates candidates, decomposes codes and learns on your device. Ordinary typing is not sent keystroke by keystroke to KOI servers.
- Local inputCandidate ranking and learning run on your device. Core input does not need AI.
- Data sharingOptional iCloud sync and AI requests have separate sharing disclosures. Preview AI context and agree before sending it.
- Service dataSDKs process diagnostic, performance and usage data. KOI uses no advertising identifier or cross-app advertising tracking.
- Your choicesSync is off by default, AI sharing can be withdrawn, and local data and images have their own clearing controls.
The privacy policy sets each of these against the implementation, point by point.
One stroke, one character
The Cangjie code for 香 is h, d, a — the radicals 竹, 木, 日. The usual way to enter it is three presses.
In KOI you drag from h to a in one stroke. The drag has to cross g, f and s on the way, and KOI knows those are not the radicals you meant. A finger that wanders still lands.
What follows is not a video. It is a working Cangjie input method running inside your browser. Tapping key by key works too, and on a laptop you can type on your own keyboard.
This demo needs JavaScript and runs locally. The page remains readable without JavaScript.
For reference: hqi gives 我, onf gives 你, hda gives 香, and etcu gives 港.
Strokes worth trying
hqi我onf你hda香etcu港nfwg鯉
Browser demo: Cangjie key layout, glide decoding and a limited dictionary. It runs locally and does not send your demo input to a server. It is a demonstration, not a complete copy of the current app.
Not in the demo: two-finger chorded entry, learning, the other four input methods, and the z wildcard. When a stroke decodes to nothing the app runs a second, best-first rescue search; the demo does not, so a meaningless stroke is told it has no reading rather than given an invented one. The dictionary is also cut down to 3,030 common characters rather than the 27,584 the app bundles.
Watch it once
The finger leaves h and drags to a. It has to pass g, f and s on the way — the red keys are the ones you meant, the teal ones you merely crossed. KOI can tell the difference.
When there is no signal
You are underground, the signal comes and goes, and the character you want is one you cannot decompose. The handwriting model is bundled inside the app — no download, no connection, nothing that waits on a signal.
KOI's handwriting area is rendered in Metal as a pool of water: your strokes leave ripples, refraction and waves. The panel below borrows the same ink: the colour under your finger here is the one the keyboard draws when you glide.
Write here with a finger or a mouse
Recognition is not in the browser — that model runs on the device — so what you get here is ink and water, and no characters. The app has a Hong Kong Traditional Chinese handwriting model built in: nothing to download, nothing to connect to, and it writes just as well in aeroplane mode.
Watch it draft one
Choose Reply, review the draft, then insert it into the text field. The receiving app controls whether and how it is sent. Choose Sticker to request a transparent-background image. This film illustrates the flow and Credit rates.
Getting started
Add KOI once in iOS Settings, then choose it with the globe key. Full Access is optional for ordinary input.
- Full AccessNeeded for AI, clipboard paste, handwriting-model updates, and shared image-library archiving. Without it, all five input methods, candidates, learning and handwriting keep working.
- Character coverageCandidates cover the Han characters in the Basic Multilingual Plane (BMP).
- Interface languageThe app interface is in Traditional Chinese (Hong Kong).