PICSimLab vs SimulIDE: Two Free, Open-Source Microcontroller Simulators Compared
Verdict: Both simulators are free and open source, so this choice is about approach, not price. SimulIDE is a real-time electronic circuit simulator: you build circuits from individual components and microcontrollers on a canvas. It is free and open source under the AGPL, sustained by voluntary donations (its support page now points to Open Collective). PICSimLab (GPL-2.0) instead emulates complete, real development boards and lets you attach ready-made spare parts to them, with MPLAB X and GDB debugging paths. If you think in terms of circuits and components, SimulIDE’s model may suit you; if your course or project is organised around a specific development board — a PIC trainer board, an Arduino, a Blue Pill, an ESP32 DevKit — PICSimLab’s board-level model matches it more directly.
At a glance
| Aspect | PICSimLab | SimulIDE |
|---|---|---|
| Price / licence | Free, open source, GPL-2.0. | Free, open source, AGPL. Development is supported by voluntary donations via Open Collective. |
| Simulation model | Board-level: pick one of 21 simulated development boards, load firmware (.hex), attach spare parts. | Circuit-level: place components and a microcontroller on a canvas and wire the circuit yourself. |
| Microcontrollers | PIC16F/PIC18F, AVR (Arduino Uno/Nano/Mega, ATtiny85), STM32F103 (two boards), ESP32/ESP32-C3, plus C51, Z80 and STM8S103 — coverage is defined per board. | PIC, AVR and Arduino-class microcontrollers among its simulated components, plus a library of electronic components for the surrounding circuit. |
| Peripherals | Spare parts system: LCDs (including HD44780 and I2C variants), keypads, 7-segment displays, sensors, DC/stepper motors, an Ethernet (W5500) part, SD card, RTCs, plus a basic two-channel oscilloscope and virtual instruments. | Components are placed and wired individually on the circuit canvas, including displays, sensors and logic parts from its component library. |
| Debugging | MPLAB X integrated debugging for PIC/AVR via the official plugin; avr-gdb, arm-gdb and esp32-gdb paths; uCsim telnet console for the uCboard. | Built-in debugging/watch facilities inside its own circuit environment. |
| Code editing | None — by design you use MPLAB X, the Arduino IDE or VS Code with PlatformIO, as with real hardware. | Includes its own code editor for working on firmware alongside the circuit. |
| Platforms | Desktop builds for Windows, Linux and macOS, fully offline; a limited official online version also exists. | Desktop application for the major desktop operating systems. |
The real difference: board first, or circuit first?
Most confusion between these two comes from expecting one to behave like the other. In PICSimLab, the starting point is a board that exists (or existed) as hardware: the McLab2 trainer with its PIC16F877A, an Arduino Uno, a Blue Pill. The board’s core circuits are fixed; your creativity goes into the firmware and into the spare parts you attach — the exact workflow of our PIC16F877A LCD tutorial and oscilloscope walkthrough. In SimulIDE, the starting point is a blank circuit: you choose the microcontroller and build everything around it, which teaches more electronics but takes longer to reach a running system.
Debugging follows the same split. PICSimLab plugs into the professional toolchains — see our MPLAB X plugin guide — so breakpoints and inspection happen in the same IDE you would use with a hardware debugger. SimulIDE keeps debugging inside its own window, next to the circuit.
Which should you choose? By scenario
- Your course uses a named trainer board (McLab2, PICGenios) or a specific dev board: PICSimLab — the board is already there, wired as the real one.
- You want to learn electronics by wiring components yourself: SimulIDE’s circuit-first model is built for that.
- You need STM32F103 or ESP32 simulation in a free desktop tool: PICSimLab covers the Blue Pill, STM32 H103, ESP32-DevKitC and ESP32-C3 boards — see our Blue Pill and ESP32-DevKitC pages for the honest scope (two STM32 chips only; ESP32 wireless support is incremental, not complete).
- You want an editor and simulator in one window: SimulIDE.
- You are not sure: both are free — install PICSimLab from our download page, try SimulIDE from its own site, and keep the one whose mental model matches your project.
One shared caution: neither tool’s simulation is the physical world. Timing, analogue behaviour and electrical edge cases differ from real silicon in any simulator, which is why both communities treat simulation as preparation for hardware, not a replacement for it.
From simulation to real hardware
When a simulated project is ready to become a physical one, the parts are inexpensive:
- An Arduino Uno or a complete ELEGOO starter kit with the Uno, breadboard and the components most beginner exercises use.
- An STM32 Blue Pill board to run the F103 projects physically.
- An electronics starter kit for breadboard prototyping of the circuit you designed.
- A USB logic analyzer — the real-hardware counterpart of the simulator’s waveform views, for checking actual signals.
These links are affiliate links routed through our /go/ redirects — see our affiliate disclosure. They never change the price you pay. SimulIDE itself has no affiliate programme; we mention its donation model above because supporting free tools you rely on is worth doing directly.