Under the keys
Every key gets a second meaning.
The mirror puts the far half of the keyboard beneath your hand. The engine turns those ambiguous keystrokes back into the words you meant.
Step one
Mirror the physical keyboard
Every key can mean itself or its partner on the opposite side. Your hand stays where it is; the far keys come to the same physical positions.
- Q mirrors to P
- W mirrors to O
- E mirrors to I
- R mirrors to U
- T mirrors to Y
This is why the raw input looks strange. With the left hand alone, typing type with one hand physically produces ttqe wetg wbe gabd.
ttqe wetg wbe gabdtype with one handStep two
Resolve what you meant
Each mirrored keystroke has two readings. A four-letter word can have sixteen possible paths. Most are nonsense; several may be real words. Hamburger narrows them in layers.
Frequency first
Common words rise above unlikely combinations before context is even needed.
Then context
The words around a candidate help settle the ambiguities that frequency leaves behind.
Then you
Your names, vocabulary, and explicit choices adapt the ranking locally over time.
And uncertainty stays visible
When candidates are close, Hamburger offers alternatives instead of pretending to be sure.
Wrong is recoverable. Hidden uncertainty isn’t.
How quality is measured
Test the system, not one flattering number.
Correction quality is evaluated against several kinds of held-out writing. Short curated sentences and realistic long-form prose fail in different ways, so both are checked on every change.
More important than a headline percentage is what happens when the engine is wrong: corrections are immediate, alternatives appear when candidates are close, and every correction can be reversed.
Where it runs
On your Mac. Full stop.
The language data ships inside Hamburger Keyboard. There is no inference server, no API call per word, and no account between you and your keyboard.
See the privacy model →Try the whole keyboard with one hand.
Use the complete app free for 30 days. No card and no account.