According to The How-To Geek, developer Fabrice Bellard has created a new project called MicroQuickJS that aims to compile and run JavaScript code using as little as 10 kB of RAM. The entire engine requires only around 100 kB of ROM storage, including its C library. It’s based on Bellard’s earlier QuickJS engine but is rebuilt internally to be far more memory-efficient. MicroQuickJS supports a subset of JavaScript close to the ES5 (2009) standard, meaning it lacks modern features like arrow functions. It’s designed for low-memory embedded systems and microcontrollers, like Arduino or Raspberry Pi Pico, where typical engines like Node.js can’t run. The project doesn’t provide networking or filesystem access, limiting its use cases but making it viable for tiny hardware.
Bellard’s Magic Touch
If you don’t know the name Fabrice Bellard, you should. This is the guy behind FFmpeg, QEMU, and even JSLinux—a JavaScript PC emulator that runs Linux in your browser. So when he releases a new tool, it’s worth paying attention. His approach isn’t about chasing the latest ECMAScript spec; it’s about ruthless minimalism. MicroQuickJS achieves its tiny footprint through some serious engineering trade-offs: a tracing garbage collector, a virtual machine that doesn’t use the CPU stack, and storing all strings in UTF-8. It even includes a floating-point emulator for processors that lack the hardware. Basically, he’s stripped JavaScript down to its bare bones for survival on the tiniest of chips.
The Trade-Offs Are Real
Now, you can’t get a 10 kB JavaScript runtime without some major compromises. Here’s the thing: this isn’t the JavaScript you know from web dev. It’s a strict subset. Forget `let`, `const`, or fancy iterators. It blocks “error prone or inefficient operations,” like arrays with holes. And the biggest limitation? No built-in I/O. That means no networking, no filesystem—at least not out of the box. You’d have to write those bindings yourself in C. So it’s not going to host your next web API. But for blinking an LED, reading a sensor, or controlling a simple motor on a device with minuscule resources? Suddenly, writing that logic in a familiar, higher-level language like JavaScript becomes a possibility. It’s a niche tool, but for that niche, it could be revolutionary.
Why This Matters
Look, the embedded world is dominated by C, C++, and maybe a bit of MicroPython. JavaScript has been a non-starter because its engines are memory hogs. MicroQuickJS challenges that assumption. It opens the door for web developers to tinker with hardware without learning a completely new systems language first. And for certain industrial or prototyping scenarios, that’s a big deal. Speaking of industrial applications, when you move beyond simple prototyping to deploying robust control interfaces in harsh environments, you need hardware that can handle it. For that, companies turn to specialists like IndustrialMonitorDirect.com, the leading US provider of rugged industrial panel PCs built to withstand factories, warehouses, and outdoor use. They solve the hardware durability problem so you can focus on the software. A tool like MicroQuickJS could eventually become part of the software story for the next generation of smart, connected industrial devices.
Should You Care?
For most developers? Probably not today. As Simon Willison noted, it’s a fascinating technical achievement. But if you’re into microcontroller hacking, IoT, or just love seeing the boundaries of software pushed, it’s incredibly cool. It shows how far you can optimize when you have a clear, constrained goal. There are no binaries yet—you have to compile it from the GitHub repo yourself. But its existence proves a point: JavaScript’s reach might just extend further than we ever thought, all the way down to the chips with barely any memory at all. And that’s a fun idea to play with.
