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Microvium is a tiny JavaScript engine (less than 16kB compiled size) for microcontrollers for running a small but useful subset of the JavaScript language. The runtime engine is portable C code and easy to integrate.

Microvium takes the unique approach partially running the JS code at build time and deploying a snapshot, which leads to a number of advantages over other embedded JavaScript engines. See concepts.md.

Take a look at my blog (coder-mike.com) and Twitter account (@microvium) if you're interested in some of the behind-the-scenes thought processes and design decisions, and to stay updated with new developments.

See also microvium.com where an installer can be downloaded (for Windows only, at this time, and this is a bit out of date -- but contact me if you want the updated version).

Install and Get Started

Check out the Getting Started tutorial which explains the concepts, gives some examples, and shows how to get set up.


See also the set of supported language features.

  • Run high-level scripts on an MCU (bare metal or RTOS).
  • The runtime engine is implemented in pure C and doesn't use any I/O functions such as fopen or printf.
  • Run the same script code on small microcontrollers and desktop-class machines (ideal for IoT applications with shared logic between device and server) -- the runtime engine is available as a C unit and as a node.js library.
  • Run JavaScript on very small devices, requiring less than 16 kB ROM and 64 B of idle RAM depending on the platform and enabled features (for more details, see here).
  • Script code is completely sand-boxed and isolated for security and safety.

There are a few similar alternatives floating around but Microvium takes a unique approach (see Alternatives).


A Microvium VM cannot exceed 64 kB of ROM and/or RAM.

There is no standard library and only a subset of JavaScript is currently supported.


Microvium can be used in 3 ways:

  1. npm install -g microvium globally will install a CLI that runs microvium scripts (and by default produces a snapshot of the final state, in case you want to deploy it)

  2. npm install microvium will install Microvium as an npm library with TypeScript definitions. This is useful if you want to run Microvium on a custom node.js host and control the snapshotting and host API yourself.

  3. Integrate microvium.c into your C or C++ project to resume execution of a snapshot.

See Getting Started which walks you through all 3 of these.



Check out ./doc/contribute.md.

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