PICSimLab Online: Run the PIC Simulator in Your Browser
PICSimLab has an official online version, so you can try the simulator without installing anything. If you searched for picsimlab online or a pic simulator online, this page is the honest starting point: the three official builds are linked below, and the limits are stated plainly, because the online version is not the full desktop application.
The online version is built from the same source code as the desktop version, compiled with Emscripten. You run it in a browser tab, load a firmware file, and watch a simulated board react — a good first look, and a good way to check whether PICSimLab fits your project before you download it.
PICSimLab Hub (picsimlab.com) is an independent, unofficial community resource site. The buttons below link to the online simulator hosted on the project author’s own pages (lcgamboa.github.io). PICSimLab is free, open-source software (GPL-2.0) by Luis Claudio Gamboa Lopes.
Choose a build: three official online versions
The project publishes three builds. They run the same simulator; they differ in speed and in how many browsers they work in. Start with the multithreaded WASM build on a desktop browser, and fall back to the others if it does not start.
| Build | Speed & compatibility (official wording) | Open it |
|---|---|---|
| WASM with multithread — fastest online build | Fast speed (about 50% of the desktop version) but worse browser compatibility: currently only tested and working in Chrome and Firefox on desktop. | Open WASM multithread |
| WASM — balanced build | Good speed and good browser compatibility. The sensible default if the multithreaded build does not run in your browser. | Open WASM |
| ASM.JS — widest compatibility | Slow speed and better browser compatibility. Use it as the last resort on older browsers. | Open ASM.JS |
How to load a program online
There is no installation and no project folder in the browser. You bring the files to the simulator:
- Drag and drop a file onto the simulator, or use its Load button, to load a
.hexfirmware file, a.pzwworkspace or a.pcfspare-parts configuration. - Many ready-made examples can be opened directly: the official examples page offers a “View Online” entry for most examples, which starts the online simulator with that example loaded.
- Select the board and microcontroller that match your
.hexfile first — firmware built for a different chip will not behave. Our guide to loading a .hex file explains the matching rules, and the first simulation walkthrough shows the full flow.
Honest limits of the online version (from the official documentation)
- No Tools menu — the desktop tools (serial terminal, modem simulator, debugger plugin helpers and similar) are not available online.
- No debugging support — no MPLAB X integrated debugging and no GDB connections. Debugging is a desktop-only feature.
- No serial communication — the only exception is the IO Vterm virtual terminal spare part. There is no virtual COM-port pair in the browser.
- Slower than desktop — even the fastest build reaches only about 50% of desktop speed. The project itself advises using the desktop version, which has more resources and higher simulation speed, especially with clocks above 8 MHz.
Online vs desktop: which one should you use?
| Online version | Desktop version (free) | |
|---|---|---|
| Install | None — runs in a browser tab | Windows, Linux and macOS builds from the official GitHub release |
| Speed | Up to about 50% of desktop (multithread build, desktop Chrome/Firefox only) | Full speed; recommended above 8 MHz clocks |
| Debugging | Not supported | MPLAB X integrated debugging and GDB paths, depending on the backend |
| Serial | IO Vterm virtual terminal only | Virtual null-modem pair (com0com on Windows, tty0tty on Linux) at 8N1 |
| Tools menu | Not available | Available (serial terminal, ESP8266 modem simulator, MPLAB X plugin support and more) |
| Best for | A first look, a quick example, a machine where you cannot install software | Real project work, debugging, serial experiments, faster clocks |
Get the desktop version
When the online limits start to bite — and for most project work they will — the desktop version is free and takes a few minutes to install. Start from the download page, or go straight to your platform: Windows, Linux or macOS. All files there link to the official GitHub release and carry SHA-256 checksums.
New to PICSimLab either way? Follow the getting started path: install, run a first simulation, pick a board, build a first project. The official online documentation is the Online Simulator appendix of the PICSimLab manual.