Korean–English keyboard · In preparation

Korean and English,without the pause.

Stop tracking which input mode you are in. Press the keys and
ChukChuk reads each word, then writes it in the right script.

Open the demoSee how
0Han/Eng presses avoided
A

0.42µs
average time per key
99.94%
word accuracy on unseen text
3.98M
Korean word forms recognized
0bytes
of typing sent out

Why it matters

One line,five switches.

Even a short work message sends your hand back and forth to the Han/Eng key. ChukChuk takes over that round trip.

  • Forget the input modeKorean words entered while the English layout is on become Hangul; English words stay put.
  • Changed your mind? One tapThe brand key restores a just-converted word to the keys you pressed.
  • Learns your habitsA word you restore on three consecutive occasions moves to the leave-as-is list.

Speed

You will neverfeel it wait.

0.42 µs per key on average: 0.0004% of the roughly 100 ms between a fast typist’s keystrokes.

Gap between a fast typist’s keys~100 ms
One frame at 120 Hz8.3 ms
ChukChuk engine, one key0.00042 ms
Too short to draw as a bar
0.42µs
  • 0.42µsmean
  • 0.38µsmedian
  • 1.0µsp99
  • 866,700keystrokes measured
Measured in this browser, right now
–µs/key

Runs as soon as the engine arrives

WebAssembly runs slower than native code. This is the same engine, untouched.

Apple M4 Max, native release build, 866,700 keystrokes of unseen text fed one at a time. On phones, the delay you notice comes from the OS input round trip, not the engine.

Accuracy

About six missesper 10,000 words.

Measured on 137,621 words the engine had never seen: 99.94% word accuracy.

Each dot is one word. Red dots are misses (about 6 per 10,000).
99.94%word accuracy79 errors in 137,621 words
99.52%sentence accuracy16,400 typed streams
0.005%correctly typed words changed by mistake1 in 19,368
529/529hand-picked hard sentenceschat, work, dev, shopping

Method

  1. Sentences were drawn mechanically from open corpora that were never used to build the dictionary (Tatoeba, Common Voice, Chatbot_data, Question_pair).
  2. Each sentence became a key sequence fed to the engine one key at a time: Korean mode, English mode, mobile auto-capitalization, and Korean running into English.
  3. The data is split into development and test sets; the test set was run exactly once, at the end.

Known weak spots

Very short words with no context around them (to vs 새, go vs 해, so vs 내) can come out wrong. One tap on the brand key restores them.

3.98MKorean word forms
320KEnglish words

Privacy

What you typestays on this device.

The ChukChuk keyboard cannot reach the internet at all. Conversion starts and ends on the device.

An offline keyboardThe keyboard never connects to any server.
Computed locallyNothing you type is sent away to be judged.
Secure fields pass throughPassword fields are never converted.
Learned words stay localWord lists and stats live only in device storage.

This site sets zero cookies and runs zero visitor analytics. The demo engine executes inside your own browser tab. Vocabulary updates are fetched by the main app, never the keyboard, as signed files. Those requests carry no user data. Full privacy policy

Customize

Shaped toyour hands.

Key height, spacing, one-handed mode, layouts and themes, previewed as you change them.

Key heightDefault
Key spacing
One-handed
Theme
ChukChuk iPhone app, keyboard customization (light)
ChukChuk iPhone app, keyboard customization (dark)
Real iPhone app screens
  • LayoutsStandard · Large keys · build your own
  • Emoji panelinside the keyboard
  • Word listsleave as is · always convert
  • Sound & hapticson or off

Vocabulary updates

New words appear,the dictionary grows.

Slang and new product names arrive as signed vocabulary packs. No reinstall needed.

Signature checkedA pack without a valid Ed25519 signature is never used.
Fails safeIf a pack is damaged, the built-in dictionary keeps working.
No user dataFetching a pack sends nothing about you.

Platforms

Five kinds of devices,one ChukChuk.

Every platform runs the same engine with the same design.

  • In preparation

    iOS

    iPhone keyboard

    Auto-switch · revert · customize

  • In preparation

    Android

    Input method (IME)

    Auto-switch · revert · customize

  • In preparation

    macOS

    Menu bar app

    Convert selection ⌃⌥Space · per-app off

  • In preparation

    Windows

    TSF input method

    Auto-switch · convert selection

  • In preparation

    Linux

    IBus engine

    Auto-switch · .deb package

Get a launch alertDownload page

Not released yet. Store links will be added here on the day they go live.

FAQ

Questions,answered ahead.

Do I really never need the Han/Eng key?

Almost never. Enter Korean with the English layout active and ChukChuk reads each word and writes it in Hangul, leaving English words alone. The demo here runs the identical engine that ships inside the apps, so try it yourself.

Where does 99.94% come from?

From 137,621 words of open sentences that were never used to build the dictionary, fed to the engine one key at a time. Development and test sets are kept apart, and the test set was run once at the end. The conditions and tables are in the accuracy section of the home page.

Does anything I type leave my device?

No. The keyboards and input methods have no internet capability, and every decision happens on the device. Learned words and stats are stored locally only.

What if it converts something I did not want?

Tap the brand key (where Han/Eng used to sit) and the word is restored to the keys you pressed. Undo one particular word on three consecutive occasions and it moves to the leave-as-is list.

When and where can I get it?

All five platforms are being prepared. Dates will be posted on the download page, and launch-alert subscribers get one email.

All questions

Open data

Data and tools we build on

The ChukChuk dictionary holds only statistics derived from open data licensed for commercial use. No original sentences ship in the app.

Full license notices