← afterhourWeb MIDI · React
GP200 Studio
A browser based editor for Valeton GP-200 guitar multi-effects presets. Load a preset file, tweak every effect on a visual pedalboard, and push changes live to the pedal over USB MIDI. No backend and no account, everything runs client side.
The buildWeb MIDI
At a glanceWeb MIDI
Built withWeb MIDI, React, Guitar, Client Side
Live atgp200studio.com
Read moreThe long versions
Valeton never shipped a Linux editor for the GP-200 and I was tired of bending down to poke a 4 inch screen. So a small UI fix for someone else's editor turned into a full browser app with 305 effects, generated pedal artwork and a manager for all 256 patches.
The GP-200 speaks an undocumented SysEx dialect, so I sniffed USB traffic with Wireshark and decompiled the official Windows editor with Ghidra. Phantom footswitch assignments, uninitialized firmware memory and one byte everyone misread for months.