Abstract : The proposed demo is a guitar pedal board coded from scratch and inspired by the Guitar FX Chrome Application 1. The demo is functional and proposes a graph based GUI for assembling effects such as: guitar amplifier emulation, Auto Wah, Delay, Distortion/Overdrive, Reverb, Chorus, etc. It includes a preset management system and saves incrementally, client side, any change in the parameters of the current preset. The latency is system and browser-dependent, but on a Mac Book Pro / Google Chrome the latency is as low as 14ms, making it playable in real time. The MVVC design is interesting for modularity and makes easy adding new effects. During the demo a guitar will be plugged into a computer using an external sound card, and the pedal board will process the sound in real-time. Lots of efforts have been put on the GUI and ease of use of the application, as well as on the core effect: the guitar amplifier simulation. The project is called " Guitar Processor " and is open source 2 .