<p>Wasmer has open-sourced <a href="https://wasmer.io" target="_blank" rel="noopener nofollow">Edge.js</a>, a JavaScript runtime that runs Node.js applications inside a WebAssembly sandbox. The pitch is straightforward: full Node.js compatibility, but with system calls and native modules isolated via WASIX (an extension to WASI).</p>
<h2>How it works</h2>
<p>Most alternative runtimes like Deno or Cloudflare Workers achieve sandboxing by replacing the Node.js API surface entirely, which means rewriting your app. Edge.js takes a different approach. Instead of sandboxing the JavaScript engine, it sandboxes only the unsafe parts - OS syscalls and native code - using NAPI as the abstraction layer. The JS engine itself runs normally.</p>
<p>The result is that existing Node.js v24 apps run unmodified. Wasmer claims Edge.js passes 3,592 out of 3,626 Node.js compatibility tests, which they say significantly outperforms both Bun and Deno on the same suite.</p>
<p>The runtime currently supports V8 and JavaScriptCore engines, with QuickJS and SpiderMonkey planned.</p>
<h2>Performance</h2>
<p>There’s a cost to the sandboxing. Right now Edge.js runs about 5-20% slower than native Node.js, and up to 30% slower with full sandboxing enabled. Wasmer says they’re targeting improvements before the 1.0 release.</p>
<h2>How it was built</h2>
<p>One detail worth noting: Wasmer says the project was built in weeks rather than years, with heavy use of OpenAI Codex. Whether that’s impressive or a little unsettling probably depends on your priors about AI-assisted development.</p>
<p>The project is open source and aimed at AI and edge computing workloads where running untrusted or third-party Node.js code safely is a real concern.</p>


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Wasmer has open-sourced Edge.js, a JavaScript runtime that runs Node.js applications inside a WebAssembly sandbox using WASIX (an extension to WASI). Unlike Deno or Cloudflare Workers, Edge.js doesn't replace the Node.js API surface — it sandboxes only OS syscalls and native code via NAPI, letting existing Node.js v24 apps run unmodified. Wasmer claims it passes 3,592 of 3,626 Node.js compatibility tests, outperforming Bun and Deno on the same suite. The runtime supports V8 and JavaScriptCore, with QuickJS and SpiderMonkey planned. Performance overhead is 5-20% normally and up to 30% with full sandboxing. Notably, the project was built in weeks using OpenAI Codex. It targets AI and edge computing workloads where safely running untrusted Node.js code is a priority.

Wasmer's Edge.js runs Node.js apps inside a WebAssembly sandbox