Simulating Everything Before Soldering Anything - Using Only Open Source Tool

So i was looking for simulation tools everything being proprietary and having to pay made me switch to open source tools

Im working on a project for a conditions called tinnitus ,where people hear a constant ringing in their ears. It affects millions in India, yet affordable treatment devices are almost impossible to find.

So before jumping into hardware my team thought of simulating results ,hardware connections ,signal precessing, different type of filter working

So these are the tools we found and worked with:

GNU Octave — think of it as the free version of MATLAB. Used to design and test the sounds the device plays to help patients.

Falstad CircuitJS1 — a browser-based circuit simulator. Used to check that the electronics would actually work before buying any components.

SimulIDE — used to simulate how the device's buttons, screen, and timer behave, without needing the physical board in hand.

KiCad — used to draw the full circuit diagram and plan the board layout, like a blueprint for the hardware.

I will be explaining on how these tools helped me in different part of project

How to use open source more efficiently and how this simulation helped before working with hardware