UnoArduSim is described as 'Provides a virtual target Uno board and allows the user to choose, and interface to, one or more of several types of virtual input/output devices' and is a Code Editor in the development category. There are four alternatives to UnoArduSim for a variety of platforms, including Windows, Linux, Mac, Android and iPhone apps. The best UnoArduSim alternative is Autodesk Tinkercad. It's not free, so if you're looking for a free alternative, you could try Autodesk Tinkercad or Wokwi Arduino Simulator.
Tinkercad is a super easy-to-use, browser based 3D design tool. With Tinkercad you can create 3D printable items: toys to play with, decoration to light up your home or jewelry to express yourself. You dream it, you can make it!
Autodesk Tinkercad is the most popular Web-based alternative to UnoArduSim.
Autodesk Tinkercad is the most popular free alternative to UnoArduSim.
A web-app you can use to simulate circuits as well as run Arduino sketches right in the browser, using the open-source AVR8js platform.
Wokwi Arduino Simulator is the most popular Windows, Android, Mac, iPhone, Linux & Android Tablet alternative to UnoArduSim.
Arduino (8-bit AVR) simulator, written in JavaScript and runs in the browser / Node.js
avr8js is the most popular Self-Hosted alternative to UnoArduSim.
avr8js is the most popular Open Source alternative to UnoArduSim.
CRUMB is an immersive interactive 3D Circuit Simulator that can be used as a learning educational tool or a prototype workspace for electronic development.
CRUMB Circuit Simulator is the most popular iPad alternative to UnoArduSim.
CRUMB Circuit Simulator is the most popular commercial alternative to UnoArduSim.
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Wokwi works on the browser, which is a major advantage compared to the Windows-only UnoArduSim. Wokwi's user interface is also more polished and modern.
However, UnoArduSim does have code debugging with support for step-into, -over and -out, and viewing the call stack.