Arduino simulators, compared honestly
- 192parts on the bench
- 25boards running now
- 1.00xreal time, on every board
There is no single best Arduino simulator, because "simulator" covers at least three different jobs: running your actual sketch on a modeled chip, drawing and checking a schematic or a breadboard without running any code at all, and doing SPICE-accurate analog analysis of a circuit that may have nothing to do with a microcontroller. A tool built for one of those is not automatically good at the other two, and most of the disappointment people report with a given simulator traces back to picking one built for a different job than the one they had.
This page compares eight real, current tools on that basis, which makes this one a comparison rather than a review: every tool has real strengths, and the honest answer for several of the questions below is a tool that is not Mokxi.
What to check before picking one
Five questions cover most of what matters. Does it run your code or only draw a circuit? Does it need an install or account? What does free include? Does it model analog behavior deeply enough for the job? And for a school, can a teacher assign a starter, see progress, check work and return feedback without stitching several tools together? The tools below answer those questions differently enough that the right pick depends on the class or project in front of you.
Tinkercad Circuits
Free, from Autodesk, browser-based, and the most widely used classroom circuit tool by a wide margin, with a large, beginner-friendly component library and both block-based and text coding for an Arduino Uno model. It is a strong first tool for a classroom or a total beginner, and a weaker fit once a project needs a board it does not model, timer-level firmware accuracy, or a breadboard at real component pitch.
Mokxi
Free to use with no account required, browser-based, and built around running your actual C++ against a cycle-accurate model of the chip rather than an approximation of it: an Arduino Uno's complete ATmega328P, or an ESP32-C3's real RISC-V core on its real memory map, both compiled and executed in the tab. The breadboard is a real 0.1 inch grid rather than a simplified drawing. WiFi uses a simulated network with no radio or real internet. Mokxi does not model Bluetooth or PCB layout, and a live circuit has no temperature or noise; those two are in its SPICE deck runner, which has no BSIM models or Monte Carlo.
Wokwi
Free for personal use and built for running embedded projects in a browser, Wokwi has the broadest maker-focused board and peripheral coverage in this group. Its official tools include simulated WiFi, an eight-channel logic analyzer, browser and GDB debugging, custom chips, VS Code integration and CI. It is a strong answer for an individual project that needs those parts or tools. Mokxi is the stronger fit when the simulator has to sit inside a class roster, starter-project, checking and submission workflow.
Proteus
A commercial, paid, Windows desktop tool from Labcenter Electronics, long established in embedded engineering education and industry. Its VSM feature genuinely runs compiled microcontroller firmware against SPICE-accurate analog circuitry in the same schematic, and it includes full PCB design tools most simulators on this list do not attempt at all. It is the deepest analog simulation on this list paired with real firmware execution; it is also the only one that is not free, and the one with the steepest learning curve, which suits a curriculum or a professional workflow better than a first project.
Fritzing
Free and open source, and worth being precise about what it is: a breadboard, schematic and PCB layout tool for documenting and designing a circuit, not a live simulator that runs your sketch or predicts what a running circuit will do. It is a strong choice for drawing up a build to share or to send off for PCB fabrication once the design is settled, and the wrong tool to reach for if the goal is watching code and hardware behave together before committing to parts.
SimulIDE
Free, open source, and a downloadable desktop application (Windows, Linux and macOS) rather than a browser tool, built specifically around simulating microcontrollers, including AVR-based Arduino boards, alongside breadboard-style circuitry with mixed analog and digital parts. It has no account, no cloud dependency and no installer size in the tens of megabytes to worry about, at the cost of needing an install and an update in the first place, which a browser tool does not.
Falstad (CircuitJS)
Free, runs entirely in the browser, open source, and built by Paul Falstad as a general electronics teaching tool: real-time analog and digital circuit simulation with live current and voltage animation, aimed at understanding how a circuit behaves rather than at running Arduino firmware. It has no built-in notion of compiling and executing C++ against a microcontroller, which makes it an excellent tool for the electronics half of a project and the wrong one for the firmware half.
Multisim
A commercial, paid SPICE simulation tool from National Instruments, widely used in university electrical engineering courses, with virtual instruments (an oscilloscope, a function generator, a multimeter) alongside its schematic capture and analysis. It is aimed squarely at analog and mixed-signal circuit analysis taught the way a university course teaches it, rather than at an Arduino project with a breadboard and a sketch; check its current licensing directly, since student and paid tiers both exist and change.
Boards and chips, briefly
Tinkercad Circuits and SimulIDE both center on the classic AVR-based Arduino boards (the Uno and similar). Mokxi models a complete ATmega328P Arduino Uno and an ESP32-C3-DevKitM-1 on its real RISC-V core and memory map, with a growing board list beyond those two. Proteus supports a wide range of microcontroller families through its VSM libraries, well past just AVR. Fritzing, Falstad and Multisim are not built around any specific microcontroller board at all: Fritzing documents whatever you wire, and Falstad and Multisim simulate the circuit's electronics rather than a chip's firmware.
Questions
Which of these actually runs my Arduino sketch?
Tinkercad Circuits, Wokwi, Mokxi, SimulIDE and Proteus (through VSM) all run real or Arduino-compatible firmware against a modeled chip. Fritzing does not simulate at all, and Falstad and Multisim are general circuit simulators without built-in Arduino firmware execution.
Which of these is free?
Tinkercad Circuits, Mokxi, Fritzing, SimulIDE and Falstad are free to use, and Wokwi is free for personal use. Proteus and Multisim are commercial products; check each vendor's current pricing directly, since it changes.
Which one should a total beginner start with?
Tinkercad Circuits for the gentlest on-ramp and the largest classroom install base, or Mokxi for a first project that already involves real C++ and a specific board like an Uno or an ESP32-C3.
Which one should I use for serious analog circuit design?
Proteus or Multisim, both SPICE-based tools built for that job specifically. Mokxi runs SPICE decks on an engine checked against ngspice, but it has no vendor model libraries, distortion or Monte Carlo analysis, and it says so plainly on its own pages.
Which one needs no install at all?
Tinkercad Circuits, Wokwi, Mokxi and Falstad (CircuitJS) run entirely in a browser tab. Proteus, Fritzing, SimulIDE and Multisim are desktop applications that need a download and an install first.
Keep going
Build this for real
Open the editor, change a value and watch the number move with it. Nothing to install, and no account needed.