#wasm

he Gecko engine compiled to WebAssembly. The real Firefox interface, rendering entirely inside this browser tab.

🦊 Firefox in WebAssembly

Private, on-device AI meeting notetaker that runs entirely in your browser — live transcription, speaker ID, and note extraction with no audio leaving your machine (WebGPU + WASM).

asm.js was Mozilla’s response to the question posed by NaCl and PNaCl: how can the web run code at native speeds? The idea was clever: pick a strict, statically-typed subset of JavaScript that an engine could recognize on the fly and compile down to native code. We could get performance similar to NaCl/PNaCl and still have code live inside web content and use web API’s (no separate sandbox, IPC, or alternative API’s). asm.js shipped in Firefox 22 back in 2013 and was a success. It let projects like Unity and Unreal ship C/C++ codebases to the web for the first time, using just standard web technologies. The Epic Citadel demo was ported to the web in just four days. It was a landmark achievement, and a fond memory for the original asm.js team.

LinuxOnTab boots a real x86 Linux kernel and Alpine userland inside your browser using WebAssembly and the v86 emulator. A zero-install, local-first, in-browser Linux terminal — a lightweight Docker alternative for instant sandboxes, teaching, demos, and disposable shells.

I use static site generators for my sites. I call out to external APIs to do anything dynamic. The exception is password protection. I'd always thought that needed to be done dynamically on a site's host server. I realized with WASM that's not the case. Files can be encrypted and served statically with a WASM process providing decryption directly on the front end.

Anyways… I’ve reached the point that my VM is fully compliant with version 2.0 of the WebAssembly core specification, and I need a large program to stress test it with. The obvious choice for this sort of thing is a DOOM port. For those unaware, DOOM runs on just about every computing environment under the sun. For every calculator, satellite, or turing-complete system, there’s likely a software engineer theorizing about how to get DOOM running on it.

Learn the WebAssembly Text Format by fixing a bunch of small programs!

On every WebAssembly discussion, there is inevitably one comment (often near the top) asking what happened. It seems to have been advertised as a world-changing advancement. Was it just oversold? Was it another JVM applet scenario, doomed to fail?

In previous posts, Davide Eynard demonstrated how to run agentic frameworks in the browser, while Baris Guler showed how to extend them with in-browser inference and support for multiple programming languages. In this post, we leverage the JVM's polyglot capabilities to create a self-contained, enterprise-optimized server-side blueprint that combines the performance benefits of WebAssembly with the reliability and maturity of Java's ecosystem.

The Azure Core Upstream team is happy to introduce Wassette: a security-oriented runtime that runs WebAssembly Components via Model Context Protocol (MCP). Wassette allows agents to autonomously fetch WebAssembly (Wasm) Components from Open Container Initiative (OCI) registries and execute them as needed. It’s built on the Wasmtime runtime, offering secure sandboxing on par with modern browser engines. To enhance security, Wassette includes a fine-grained, deny-by-default permission system, allowing interactive control over access to system resources.

As much as I can justify it, this project is probably going to be useless to most people. Not many people are seriously going to play all of celeste or terraria in the browser, and the novel things we did discover along the way are probably too niche to be of any help to anyone else.

Finally, we reach the juicy part. My favorite way to use WebAssembly is as a way to share code between platforms. Write the core logic of your application in Ru… a language that can easily compile to native code and WebAssembly 😊. In this architecture, most of your code is shared between the “native” and the “web” variants of your app. Maybe some platform-specific features will need to be turned on or off with compile-time flags, but if you’re building a cross-platform app, you are probably already dealing with different code paths for different platforms anyway. With WebAssembly, the web just becomes another platform to target!

Run a full Postgres database locally in WASM with reactivity and live sync.

MicroW8 is a WebAssembly based fantasy console inspired by the likes of TIC-80, WASM-4 and PICO-8. The initial motivation behind MicroW8 was to explore whether there was a way to make WebAssembly viable for size-coding. (Size coding being the art of creating tiny (often <= 256 bytes) graphical effects and games.) The available examples so far are all in this space, however, I very carefully made sure that all design decisions make sense from the point of view of bigger projects as well.

The framework for building with WebAssembly (wasm). Easily load wasm modules, move data, call functions, and build extensible apps.

Model Context Protocol on steroids ;)

So in this guide we’ll walk through setting up the tooling and development environment for building and using WebAssembly in Rust, embedding it in a TypeScript project, review how communication between TypeScript and Rust can happen, then finally how you can debug your WebAssembly directly in the browser and/or your favorite IDE. I will use Visual Studio Code as the IDE and Chrome as the browser, but apart from some debugging options, you can reproduce these in your tool of choice.

WebVM is a server-less virtual environment running fully client-side in HTML5/WebAssembly. It's designed to be Linux ABI-compatible. It runs an unmodified Debian distribution including many native development toolchains. WebVM is powered by the CheerpX virtualization engine, and enables safe, sandboxed client-side execution of x86 binaries on any browser. CheerpX includes an x86-to-WebAssembly JIT compiler, a virtual block-based file system, and a Linux syscall emulator.

Today we are incredibly excited to announce full support for Node.js/Bun in @wasmer/sdk, after one member of our community asked about it on Wasmer’s Discord a few weeks ago.

And to be clear I don't mean the Common Gateway Interface as a protocol. I mean what CGI and the cgi-bin application model brought to the web. They allowed people to easily write code that makes websites interactive. This shifted the web from an archive of documents to a vast network of applications. It was the first "web application model". I think Wasm (WebAssembly) is setup to bring the next "web application model" to the industry.

The solution is wasmati, a TypeScript library to write Wasm at the instruction level. The wasmati API looks exactly like Webassembly text format (WAT).

The solution is wasmati, a TypeScript library to write Wasm at the instruction level. The wasmati API looks exactly like Webassembly text format (WAT).

This is the useful app, which is a bit more complex than “Hello, World!”. This app can help to generate different passwords for every service. You need to remember your keyword and the length of password only.

This is the useful app, which is a bit more complex than “Hello, World!”. This app can help to generate different passwords for every service. You need to remember your keyword and the length of password only.

After seeing the examples on hellorust.com, I thought it would be interesting to try to adapt my game Rocket to work on the browser through the wasm32-unknown-unknown target. The project was a great way to figure out how far you can go when porting a project that is a bit more complex than a hello world. I was pleasantly surprised by the fact that most of the code could be reused. Particularly, the game logic code was barely touched at all.

After seeing the examples on hellorust.com, I thought it would be interesting to try to adapt my game Rocket to work on the browser through the wasm32-unknown-unknown target. The project was a great way to figure out how far you can go when porting a project that is a bit more complex than a hello world. I was pleasantly surprised by the fact that most of the code could be reused. Particularly, the game logic code was barely touched at all.