SARU KX78HE keyboard software
Remap keys, set the RGB, record macros and change device settings on the SARU KX78HE. Free and open source. Use it in a Chromium browser with nothing to install, or download the desktop app for Windows, macOS or Linux. Either way it runs entirely on your own machine: no account, and the browser version makes no network requests once the page has loaded.
What sharkfin does with the KX78HE
- Remap any key. Click a key on a picture of the board and give it another key, a mouse button, cursor movement, the scroll wheel, a macro or a media control. Base and Fn layers both. 4 onboard profiles.
- Lighting. 18 backlight effects with direction options, full RGB colour, brightness and speed. The effect runs on a picture of the board as you change it; a slider writes to the board when you let go of it.
- Per-key colour. Paint individual keys and send the pattern to the board's flash.
- Macros. Record key and mouse sequences with per-event delays into the 50 onboard slots, then bind a key to one.
- Sleep timers for 2.4 GHz and Bluetooth, plus deep sleep.
- Device settings. Windows-key lock, WASD and arrow-cluster swap, backlight off, host-OS auto-detect and a factory reset, all from the Device page.
- Backup. Export everything to a file and restore it later.
- Magnetic switches. This board has them. The Switches tab reads and writes actuation point, release point, rapid trigger, dead zone and the advanced kinds per key; on yc500 boards the columns need firmware 2.00.
The picture sharkfin has for the KX78HE knows the board's shape but not yet which internal slot each key lives in, so the first connection includes a check: the drawing is matched against the keymap your own board reports, you confirm it once, and from then on you remap on the picture. Until then the app shows a plain grid. The check exists because two boards can share one picture and still disagree about which slot a key lives in, and a wrong guess would send a remap to the wrong key. sharkfin trusts your keyboard over its own files.
KX78HE at a glance
| Brand | SARU |
| Model | KX78HE |
| USB ID | 3151:5030 |
| Device ID | 3243 |
| Protocol family | gen2 |
| Settings writable | yes |
| Drawn layout | after a one-time check |
| Onboard profiles | 4 |
| Backlight effects | 18 |
gen2 and yc500 are the two command sets these keyboards speak. The same command can mean different things in each, so sharkfin never guesses: the board names itself when it is plugged in, and the command set follows from that.
Connecting
Plug the KX78HE in with a USB cable. Over a 2.4 GHz receiver sharkfin reads whatever the receiver relays: some carry the settings channel, some carry nothing, and the same model ships with both, so plug the receiver in and the app says which yours is. Writes need the cable. Bluetooth has no settings channel. Settings are stored on the keyboard itself, so everything you change keeps working wirelessly once you unplug. sharkfin never flashes firmware. On Linux, the AppImage and the browser build need a one-line udev rule before they can open the keyboard; the .deb and .rpm install it. And if you are hunting for a polling-rate or report-rate setting: there is none in sharkfin, because this hardware does not expose one.
If the KX78HE stops responding
It happens: the firmware stops answering and the app says the board needs a replug. Typing keeps working the whole time. In order:
- Close sharkfin, or the browser tab. While either is open it keeps trying to reach the board.
- Unplug the cable, wait ten seconds, plug it back in. The board needs to lose power, not just reconnect.
- Fn + Home turns the lighting back on if the backlight looks dead.
- Fn + Esc, held for about three seconds, resets the board's settings.
- Still wrong? Open sharkfin and use Device, then Factory reset.
None of this touches firmware; nothing here can leave the KX78HE unusable.