Velxio is an electronics and microcontroller simulator that runs in your browser. Its core is open-source (AGPLv3) and you can self-host it; the hosted version at velxio.dev adds a few extras on top. If you are choosing a simulator, you are probably weighing it against Wokwi, Tinkercad, Proteus or Fritzing. This is an honest comparison: what each tool does well, where it falls short, and where Velxio fits.
We will say plainly when another tool is the better choice. A comparison that only flatters the author is not worth reading.
A note on Wokwi
Velxio owes Wokwi a real debt. Wokwi showed that cycle-accurate microcontroller emulation could live in a browser, and the Wokwi team open-sourced core engines — such as AVR8js and wokwi-elements — that a large part of this ecosystem builds on, Velxio included. That is the respect and the inspiration, stated once and meant sincerely.
What follows is not a knock on Wokwi. It is a description of two different philosophies: a polished cloud product on one side, and an open-source, self-hostable project on the other.
At a glance
| Tool | License / cost | Where it runs | Strongest at |
|---|---|---|---|
| Velxio | Open-core: AGPLv3 core + commercial licence | Browser (velxio.dev) + self-host (Docker) | Multi-board emulation, real analog (SPICE), self-hostable core; AI agent on velxio.dev |
| Wokwi | Proprietary, free + paid tiers | Cloud (browser, VS Code) | Language breadth (MicroPython, Rust, Zephyr) and a mature VS Code flow |
| Tinkercad | Proprietary, free | Cloud (browser) | Absolute beginners, classrooms, breadboard basics |
| Proteus | Commercial, paid (one-time) | Windows desktop | Professional mixed-signal simulation and PCB design |
| Fritzing | Open-source (GPL) | Desktop | Breadboard and schematic diagrams, PCB documentation |
Velxio vs Wokwi
Both run real firmware in the browser and share some of the same underlying engines. The differences are about ownership and scope.
What Velxio adds:
- Open-core and self-hostable. Velxio’s core is AGPLv3 and dual-licensed (a commercial licence is available for uses that can’t meet the AGPL’s terms). You can read the code, run the Docker image on your own server, and keep your projects on your own infrastructure. Wokwi is fully proprietary and cloud-only.
- Offline. Velxio runs locally — useful for classrooms, labs, and travel. With Wokwi, offline use is tied to its paid VS Code plan.
- Real analog (SPICE). Velxio co-simulates digital firmware with a real analog engine (ngspice compiled to WebAssembly), so a transistor, op-amp or RC filter behaves like the real part. This is a different class of simulation from digital-only pin logic.
- AI agent that helps design and debug circuits and code. Note this is a proprietary, hosted feature on velxio.dev — it is not part of the open-source, self-hosted image.
- Architectures first-class: AVR (Uno/Nano/Mega/ATtiny85), RP2040 / Pico W, ESP32 family (Xtensa), RISC-V (ESP32-C3, CH32V003), and a full Raspberry Pi 3 Linux target.
Where Wokwi leads — honestly:
- More languages. Wokwi supports MicroPython, CircuitPython, Rust, Zephyr and ESP-IDF. Velxio today is Arduino C++ and Python.
- A mature VS Code extension with a full debugger, plus CI integration and team billing. Velxio’s editor integrations are earlier-stage.
- Maturity and community built over years.
| Wokwi | Velxio | |
|---|---|---|
| Open-core / self-host / offline | No | Yes (AGPLv3 core + commercial) |
| Real analog (SPICE) | No | Yes |
| AI agent | No | Yes (hosted on velxio.dev, proprietary) |
| Custom chips in C / Rust | Limited | Yes |
| MicroPython / Rust / Zephyr | Yes | Arduino C++ / Python |
| Mature VS Code extension + CI | Yes | Not yet |
| Years of maturity and community | Yes | Growing |
Choose Wokwi if you need MicroPython, Rust or Zephyr, or its established VS Code and CI workflow. Choose Velxio if you want an open-source core you can self-host and run offline, real analog simulation, or the hosted AI agent on velxio.dev.
Velxio vs Tinkercad
Tinkercad Circuits (by Autodesk) is the friendliest on-ramp in the whole category. Drag-and-drop breadboard, a handful of basic components, and an Arduino Uno — ideal for a first LED or a classroom of beginners. It is free and needs nothing but a browser.
Velxio targets the step after Tinkercad. Where Tinkercad stops at the Uno and basic parts, Velxio adds ESP32, RP2040, RISC-V boards, 100+ components, custom chips, instruments (oscilloscope, voltmeter, ammeter) and real analog.
Choose Tinkercad to teach someone their very first circuit. Choose Velxio the moment you outgrow the Uno or need behavior closer to real hardware.
Velxio vs Proteus
Proteus (Labcenter) is a professional, paid Windows suite. For deep mixed-signal simulation and full schematic-to-PCB design, it is more powerful and more mature than Velxio, and we will not pretend otherwise. It is also a desktop install with a license cost that runs from a few hundred to several thousand dollars.
Velxio sits at the other end: web-first, open-core, and instant — free to use, no install, shareable with a link, and self-hostable for a team or a school.
Choose Proteus for professional PCB work and the deepest analog accuracy. Choose Velxio for fast, accessible, shareable simulation and emulation without a license or an install.
Velxio vs Fritzing
Fritzing is a much-loved, fully open-source tool — and Velxio’s core is open-source too (AGPLv3), a value we share. But it solves a different problem: Fritzing is for drawing breadboard layouts and schematics and for designing and documenting PCBs. It is not really a code simulator.
Velxio actually runs your firmware and simulates the circuit’s behavior over time. The two are complementary: document and lay out a build in Fritzing, then run and test the code in Velxio.
Choose Fritzing to draw and document a circuit or design a PCB. Choose Velxio to compile, run and simulate the firmware.
When to choose what
- Brand new to electronics? Start with Tinkercad. Move to Velxio when you want more boards and realism.
- Want MicroPython, Rust or Zephyr, or a mature VS Code + CI flow? Wokwi.
- Need professional PCB design and the deepest analog accuracy? Proteus.
- Documenting a breadboard build or designing a PCB? Fritzing.
- Want an open-source core you can self-host and run offline (with real analog), or a hosted version with an AI agent? Velxio.
How Velxio is licensed
To be precise about the “open-source” claim above, Velxio is open-core and dual-licensed:
- The simulator core — the in-browser emulator, the boards, the SPICE engine, the editor — is open-source under AGPLv3. You can read it, modify it, and self-host it (the Docker image) under the AGPL’s terms.
- A commercial licence is available for organisations that can’t or don’t want to comply with the AGPL (for example, building a closed-source product on top of it).
- Some features of the hosted service at velxio.dev are proprietary — most notably the AI agent, which is not part of the open-source image and runs only on velxio.dev.
So “open-source and self-hostable” is true of the core; the AI agent and a few hosted extras are not open-source.
Try Velxio
- Open the editor in your browser: velxio.dev
- Read the source or self-host it: github.com/davidmonterocrespo24/velxio
If Velxio is useful to you, a star on GitHub genuinely helps more people find the project.
Comparison written 2026-06. Tools change quickly — pricing and feature details for Wokwi, Tinkercad, Proteus and Fritzing were accurate to the best of our knowledge at the time of writing. Sources: wokwi.com/pricing, docs.wokwi.com, tinkercad.com/circuits, labcenter.com, fritzing.org.
